Well it happens to be that exactly. Your data is not gone but is damaged beyond recognition. You need to start over. All my games have a separate cloned saved file in a flash drive (except for the Dead or Alive games which Team Ninja is an idiot about piracy and taking it to the extreme as to not allow a copy of a saved data) which is where a copy of all my dlcs are also and some game installs there too. I'm also going to use a xbox explorer which I have to copy data to the pc for extra safety. Most likely it happened by a power failure during a save or perhaps a dashboard in the middle of a save. It can also mean a memory unit/harddrive/flashdrive problem. You can also clone them and transfer them from the harddrive to the internal memory unit. Internal one is small but game saves are very small so no biggies there. It has never happened to me. There was a supposed memory card saved problem with Soul calibur 3 back in the PS2 era I have the game since launch and saved in 3 different memory cards. I have done what was suggested it could cause corruption. Till this day all 3 saves are okay. So It might be a problem or an unseen event on your side. Backup is your best friend buddy. I suggest you backup all your games including RE6 after you start over.
Wowsers, Sherry Birkin got really cute after Racoon City My dream of seeing Talim Grown Up has been destroyed!