So I know this has been posted a few times, and the only solution I've seen is to import the corrupted file into a new project (which unfortunately didn't work for me).
I had about 3-4 hours into a logo animation I was making for a client yesterday before calling it quits for the day, and no matter how many times I hit save, when I'd try and exit AE, it would ask if I would like to save my changes, even though I just saved a split second ago. Right there I should have known something was wrong, because then this morning when I tried to reopen my animation, bam, the terrible Error 33::4 Missing Data in File. Same with the ten most recent auto-saves out of the twelve total I had.
I was wondering if anyone knows the root of this problem? Could it of been because I'm using Element 3D? Maybe because I'm saving to an external drive? It's just frustrating because this is not the first time it's happened to me.