[SOLVED] All collisions in game stopped working

Hello everyone,

Is it possible for an unity project to get corrupted? For some reason this morning after working on a couple classes, ALL other classes involving collisions in the game stopped working. They're now giving me NullReferenceException where the version before this one still works, but I have not touched the code of those other classes.

Thanks

UPDATE: I wonder if it is a bug, I've just noticed that most tags of my game are gone.... that was causing some of the problems, but some collisions aren't working still.

UPDATE2: Somehow a component under my player got removed and I did not notice it. Still odd how it happened though;