Warnock was England's number two left-back at the 2010 World Cup finals and then won the second of his two caps against France at Wembley.
But he was banished to training with the reserves by Houllier and only now has returned to the first team under the current Villa manager Alex McLeish.
Warnock, speaking in Villa's official programme for Saturday's match with Wigan, said: "It was very difficult but I was very lucky to have (coach) Kevin MacDonald with me when I was training with the reserves.
"He kept me on top of my game and told me to keep fit and make sure my head was right. He said 'you never know what is going to happen in football'.
"He was great. He kept us ticking along and the young lads were great with me as well.
"It was good at times because I was helping to develop the young lads and passing on a bit of knowledge to them.
"But it was also frustrating and I never want it to happen again. That's why I'm so hungry to do well this season."
Warnock is determined to recapture the form he showed at Blackburn and in his early days at Villa under Martin O'Neill.
He said: "My best form was when I was at Blackburn and when I got my move here.
"In my first six months at Villa, before I got injured, I was playing as well as I ever have.
"Hopefully I can get back to that level. I know I can do it if I get a run of games and keep my fitness up."
Source: Team Talk