"You're a money grabber", "You don't respect the shirt", "You're a virus, you are killing this club".

Those were the kind of messages I was getting every day on social media during the final months of my time at Aston Villa, and of course they hurt.

I would be wondering how anyone could say that about me if they knew where I had come from, how hard I had worked, and what I was like as a person.

But when you are an injured footballer, especially when you are out for as long as I was, you find out all about the dark side of the game.

I was in a lonely place for a long time, and I did not know how to get out of it.

I am a pundit now, not a player, but when I was getting abused by Villa fans on Twitter and Instagram, I was still battling to save my career.

Deep down, I probably knew it was already over, but for most of the two and a half years between my 295th and final game as a professional, against Wolves in October 2016, and the day I announced my retirement in July this year, I was living in denial.

I would keep on waiting for each new manager to come in at Villa and say to me 'I'll give you a chance', but it got to a stage where that could never happen, because although I could train 100%, I was never able to play.

I could run and I could jump - but I couldn't twist on my right knee, and it would not get any better. Whatever I tried, it did not make any difference.

Richards in pre-season training with Villa in the summer of 2017

You don't get taught how to deal with the end of your career

There were times while I was injured at Villa when I felt like I was a ghost.

They told me to come in three times a week, then two. Then one. I would stay at home waiting for the club doctor to text and say when I was needed.

I got looked after brilliantly by all the medical staff there and I know the intention was probably to help me out, to save me travelling in, but it left me a lot of time on my own to think.

All I wanted to do, still, was play football but I was fighting thoughts that my knee was never going to be good enough to do that. The fans were getting frustrated with me. And of course you also start to think that the club don't really want you there.

I was not seeing much of my team-mates at the time, because I wasn't training with them. But even when I did, I would never talk about my emotions or express my feelings, so anyone talking to me at the time never truly knew what was going on.

Richards in the gym at Aston Villa's Bodymoor Heath training ground on the day he was unveiled as their new signing in July 2015

As a player, you worry about a lot anyway, but all footballers put on a front. I have played with players who I think have been depressed, and I have seen people just go 'oh, they will be all right'.

It is the same away from football. When you are a successful footballer, you get put on a pedestal. You are the person your friends and family look up to, and they do not know how to approach you when things are going wrong, even when you just need someone to reach out to you and ask you if you are all right.

The perception is you are a man, you are an athlete, and you are extremely well paid. You are supposed to be doing great.

I don't want to say I was depressed myself, because there are people I know who have had issues with their mental health and have suffered from depression and I don't think what I went through was on the same level.

I always tried to stay positive, and keep a smile on my face... but I needed help.

There was a time for a few months where I was coming into training just for a gym session on my own. Steve Bruce, the manager at the time, would sometimes see me and say to me "I am worried about you" but each time, me being me, I would tell him I was fine. I really wasn't.

I would go into the gym and tell myself "I am all right, I am all right, I am all right" but actually I had no idea how to deal with what was happening to me, and my body.

I am a very positive person, but you don't get taught how to deal with the end of your career. Never.

A teenage knee injury and the training run that started the downward slope

Richards tackles Carlos Tevez during City's win over United in the Manchester derby in August 2007

I made so many challenges, I don't even know when I first damaged my right knee.

But I know the problems with it that eventually forced me to retire started when I was still a teenager.

It was the beginning of 2008. I was 19, playing for England and City and living the dream. I loved every minute of the ride at that time; it was amazing.

Then I got some swelling there after a game. I played through the pain for a bit but then I had to go and get it scanned. The doctor said it was not too bad; the cartilage just needed shaving down.

So I did that, had my first operation on it, and I was out for four months. But from there, instead of getting better, that knee just got gradually worse and worse.

Even so, I could manage it and still play regularly - I was City's first-choice right-back when we won the Premier League in 2011-12.

But, early in the 2012-13 season, in a game against Swansea, I hurt it again. I knew straight away it was bad because the knee was locked and I could not straighten it. I had torn my meniscus, so I had more surgery and I was out from October until April.

Richards is carried off after injuring his knee in Manchester City's 1-0 win over Swansea in 2012

From then on, I started getting other injuries because of my knee - my hamstring kept going. But I could manage it, and if I treated it correctly, and trained the right way, I could play.

Fast forward a couple of years and when Tim Sherwood signed me for Villa in 2015, he was brilliant. He knew what I needed to do in training, and I played every game for him.

But then he was sacked and Remi Garde came in.

He told me that if I couldn't do what he asked me to do in training, he couldn't pick me. As Villa's captain, I understood that. I felt I had to do what he asked, and I would never say no to my manager in any case.

So I said: "OK, I'll do it." I still remember that day - we ran for miles, around a kind of obstacle course. Obviously I was at the back, because my back was hanging off and my knee was very sore.

I got through it and he said "you did well" but I was just thinking: "You have made me do that and you don't know what damage has been done."

From that day on, the swelling started coming back on my knee whenever I did anything. I felt like I was on a downward slope and I didn't know how to stop it.

'The end. No doctor ever told me I was done'

Because he only played me once, in his first game in charge, people seem to think Steve Bruce did not give me a chance at Villa, but that's not true.

Before he arrived, in October 2016, I had not been training much because of the swelling but I actually managed some proper sessions when he took charge and my knee was coping with them.

A game is very different, though. I lasted 66 minutes against Wolves and my body was hurting when I came off. I sort of played it down as being fatigue because I had played so few minutes over the previous few months, but the next day, my knee had blown up, and it was bad.

Richards had played only 152 minutes of football in the 2016-17 season before his final appearance as a player on 15 October 2016

Steve was very good to me and said I needed to go somewhere I could play once a week and manage my knee correctly. I tried to get out, and I had offers, but Villa wanted money for me - and nobody wanted to pay.

He did not give up on me until the following summer, though. In that pre-season of 2017-18, I pulled my hamstring in the first five minutes of our first friendly game and I think that is when he lost faith in me. He told me that I was running in a weird way because of my knee and that was impacting me with other injuries.

I was back fit again after 10 days and able to play so I was telling him I was ready, but by that time everyone else in the squad was fitter than me and I kept getting little niggly knocks, so I was never fit.

By the time Dean Smith took over, in October 2018, I had not trained for three or four months.

Again, with him I was thinking 'new manager, new chance' so I went outside for a training session. I thought I did OK, but obviously my heart-rate was being monitored, and everything else.

Everyone else was running 5km or 6km, but I only managed around 4km. Dean spoke to me honestly afterwards and said: "Look, I'd love to give you a chance in the team but you are nowhere near as fit as I need you to be. You are miles away from having the numbers you need, and it is not going to happen."

I actually respected him more for telling me that. Although it wasn't what I wanted to hear, it was then that I knew my career was probably over.

But no doctor ever told me that I was done. I kept getting told that my knee was in a really bad way, but also that there were other people who had managed to continue playing by looking after it the right way.

Me being me, I always gave it a go. I guess I did not want my career to end, but this summer I had to be realistic about it.

It would have been easier to take if I was just no good any more, but I had to realise that my knee was never going to allow me to do what I wanted.

It was time to give up the fight, and I was ready for a new challenge.

I never fell out of love with football

Richards (front) played right-back in 29 of City's 38 games in their 2011-12 Premier League title-winning campaign

Now I am a pundit, I want to talk about this part of the game and the effect it has on you, give my perspective on what is happening to current players and share my own stories that people might not know.

I can look at everything from the other side now. I am only 31, but I know all about the pitfalls of being a professional footballer - the ups, and the downs.

I could sit here and look back and think I wish I had done this or that, because I definitely made some mistakes along the way, but I am actually very proud of what I achieved.

I won 13 England caps, a Premier League title and and an FA Cup, plus I played more than 250 games for City, had a spell abroad and then played for Villa in the city where I was born.

Richards celebrates a goal for England against Israel, aged 19 years and 76 days. He is still England's youngest defender after making his debut at 18, and is their sixth-youngest scorer after Wayne Rooney, Michael Owen, Marcus Rashford, Tommy Lawton and Alex Oxlade-Chamberlain

The past few years have been difficult and the end, when it came, was something of a relief but it is not as if I ever fell out of love with football, quite the opposite in fact.

Throughout all of this, I was determined I would not become a negative presence at Villa, no matter what happened.

Whatever Villa fans think of me - and they can question my ability and whether I was good enough, because sometimes when I played for them I wasn't - they can never question my professionalism, whether I was injured or not.

Towards the end of the 2015-16 season, when we were relegated from the Premier League, Eric Black became caretaker-manager and I got dropped, but I was captain and I wanted to try to continue to be a positive influence on the dressing room.

Eric called me in and told me my attitude was absolutely spot-on. He said he could not believe how good it was, really, because he had left me out of the team.

I said to him: "Well what do you expect from me? How do you think I got this far in my career? It is not by luck."

I told him I have had a good attitude right from the start, because I've had to. I grew up in a part of Leeds called Chapeltown where opportunities are not handed out very often.

When I was a kid, I decided I was never going to let myself down and lose out on anything by having a bad attitude, and I have always stuck by that.

Since retiring in July, Richards has combined punditry work with a promotional role at Manchester City

Yes, things can get me down, but I will never deliberately disrupt an environment or have a negative effect on other people. It is not the way I was brought up, and I don't think it is fair. If you know me, you'll know that.

When I look back on my career, I know things could have gone better but I know I always gave everything I could, and I am content with that.

Now, as an ex-player, I am in a happy place again, which is the most important thing.

I just feel so lucky that I am still involved in the game and, in my new role, I will hopefully be able to explain what life as a footballer is really like.

Micah Richards was speaking to BBC Sport's Chris Bevan.