Actually I...Permanately deleted the AppData Folder. If that's anything to go by...
Update: You know what? I think I'll stick with downloading games from the website. -_-
If you deleted the entire AppData folder then you may have caused an issue with your operating system. Can you try recreating it? It should be fine if it's empty. Many programs you've installed probably depend on it existing.
Okay, I made a new AppData folder in (C:) Drive. Now what?
