Back At The Begging

"Damon was not really sure how it happened, maybe Bonnie had been working on a spell that had gone wrong? Or maybe it was just a random act of God, who knew. All he knew was that one moment he had been eating breakfast in the kitchen in the year 2034. And the next minute he was back in Mystic Falls Virginia, in the year 2009."

Or

Damon is sent back in time to season one of The Vampire Diaries. He has a chance to try and fix some of his mistakes and save the life of his brother and many others. So that is what he does, or at least he tries too. He is Damon Salvatore after all, life does not always go his way.