Warner was left out by previous coach Mickey Arthur following a drunken altercation with England batsman Joe Root in a Birmingham nightclub, an incident that helped persuade Cricket Australia to sack Arthur soon after.
The 26-year-old has conceded that he feels guilty over his role in Arthur's dismissal, while admitting that he cried on the phone to his mum soon after the news hit home.
He told The Guardian: "I rang my mum and dad and told them I wasn't playing. And I kind of broke down on the phone to mum. It's just one of those things you ask your mum and dad, what could I have done better in those situations?
"You don't want to really go into it as much but I've matured a lot since that incident. It was massive to miss a Test. As a kid growing up, you want to play in the Ashes and, after that incident, I went back to my room and I was pretty shattered for a week and a half, two weeks.
"I still feel the guilt of what happened. I feel myself it's led to me being in this situation at the moment. Things would have been different, I would have been able to play those warm-up games and I could have pressed my claims to play in this first Test, but that's me."
New coach Darren Lehmann has decided to allow Warner join Australia's A side for two matches against Zimbabwae and South Africa, with a view to returning for the third Ashes Test at Old Trafford next month.