Make a back up often, It's totally needed if you make a couple of new maps or add some stuff that took allot of time. I know one time a version of my game broke and it wouldn't work at all. Best to keep your work safe.
i definitely will make backup more often, things can go very bad indeed. this is the 2nd time actually and i got my lesson this time .
how did you manage to get it to work back again or you had to do lot of things again?