>I have a project with a bad .pjt file. I need to recover it. How do I get my project back??? Also, why did this happen?

Something like a network break can cause it...anyway, it's usually not worth trying to fix a corrupted project, IMO. Just creating a new one is generally very simple, it will pull most of the contents in automatically on a build.

Or, just grab a backup, simplest method of all.