I need help fixing an error when I downloaded something(Materials fucked up)

So I downloaded this:
http://www.facepunch.com/showthread.php?t=46638&highlight=high+resolution
It replaced the materials of the main hl2 characters.They weren’t even high res ffs. Now when I spawn some ragdolls it crashes my gmod. I don’t know where to get the original materials. Do I have to reinstall gmod or something? I have no idea about these things!