That exact same thing happened to my brother on the PS3 version. I did some research and apparently thats a common problem with this game. Everyone should back their saves up when playing it.
Before anyone starts pointing their finger at the thread title, I'm aware that there's no trading in this thread but I'm unable to post in the trade thread for some reason (perhaps because this account is new) so I have no choice. I have little time to make this deal.
Anyway, I have a download...