http://www.infinityward.com/forum/viewtopi...24&t=340310
http://www.infinityward.com/forum/viewtopi...24&t=340772
tl;dr
First link contains a mod cleaner that will remove unwanted mods that alter game files and make things unplayable.
Second link contains a tool that allows you to create back ups of your stats. I can vouch for the Backup Tool. I use this myself every time I exit the game to ensure that I can reverse any alterations to my stats in the event that I join a hacked server.
Edited by Stinger, 07 July 2010 - 22:52.