Before her death, Amy Winehouse seemed to have her life back on track. She had a new boyfriend, Reg Traviss, she had gained some weight, was healthy and even sang a duet with Tony Bennett. But she was still on again, off again with the booze.
Winehouse's final performance, in Belgrade, Serbia, was one of her worst. She was drunk and chaotic on stage -- an emblem of demise, and not what could have been.
Then, in the final two days before she died, the singer drank a fatal amount of alcohol, something that puzzles her father to this day.
"Who knows what makes anyone do anything to the extreme. I have no idea," Mitch Winehouse said. "There would obviously have been more music, and she would have married Reg, and there would have been children, just like any other normal couple. But it wasn't to be."
Amy Winehouse released just two albums in her lifetime. Then a posthumous collection of mostly unreleased and unfinished songs was released in December, which earned her a Grammy this year. Her parents accepted the award on her behalf.
"I regret my daughter's passed away," Mitch Winehouse told ABC News. "I suppose I could have handled certain situations better than I did."
"Our Day Will Come" was Amy Winehouse's last single.
All of the proceeds from her father's book, to be released on June 26, will go to a foundation in her honor.
Watch the full story on "Nightline" TONIGHT at 11:35 p.m. ET