How do I revert my settings after using an autoexec?

So I downloaded some FPS pack which had an autoexec with bunch of commands. It made the game look terrible, and didn't really increase my fps much. So, I deleted the autoexec and removed -autoexec from my launch settings. But the game still looks terrible. I even deleted and reinstalled the game, but there is no difference. Is there any way I can restore all these settings to the default values so my game can look normal again?