I have no memory of the "Do Over" event but the main male character wakes up in the body of his teenage self still retaining his future memories.
In his original time, girl friend was dying of some type of cancer. The sick girl moves away or they part before her illness is apparent which the main character regrets in his later years. I believe there was mention of a letter explaining the reason to the main character.
In his 2nd time, the main character confronts the sick girl and ends up telling her the truth about having memories of the future.
If I am not mistaken the main character starts a band. I believe music was a part of the story line. I could be mixing this up with another story.
Hope someone can help.