After installing BO3, some of my legit steam games don't work properly anymore.

I recently installed BO3 from fitgirl-repacks.site (i ensured it was the legit site) and now I cannot launch or play some of my steam games. Battlefield 4 comes up with a winmm error saying "Launch the game as admin" and even though I do it brings up the same error. Elite dangerous now says that I need to provide a product key because apparently my frontier account doesn't own the game. Any help on this would be appreciated.