My Nephew did the same thing.
I gave him one of my guitars all set up and it played beautifully. A year later he asked me why it it was buzzing and hard to play... I found out he never kept it in its case and just leaned it against the wall in a corner. He thought he knew what the truss rod was for and cranked it as tight as it would go... He also carved into the top where both E strings were so he could remember where they were!!! Dents, chips and scratches, he pretty much destroyed it.
Needless to say, he doesn't have it anymore...
Bob