Since that's spammed and easy to find with google, let's make this a spam free zone. No links,
As any project manager knows you keep backup copies for when this happens. Sometimes the manager needs to lose it all a few times until they accept that backups are not optional.
I can't guess if you turned on the backup feature. Here's the picture:
Full article at http://ntrajkovski.com/2015/07/09/how-to-protect-your-project-file-with-ms-project-2013/
I have a MS Project file (2013 .mpp format) with many procedures, user forms, etc. The file has corrupted by unknown reason and now I cannot open it at all.