not sure what you have tried but if its been installed on your pc the whole time some of the files may have become corrupt or even accidentily deleted, I would uninstall and if for some reason it wont let you uninstall delete the dir on your harddrive and delete keys in registry portaining to the game if you know how to do that. Then try a fresh install, and if that doesnt work I have no idea. If you wanna play really bad the one with 5 expansions is only $30 i think. Goodluck.