Open the steam interface and right mouse click on the game guru icon from your library.
Choose properties.
Local files tab.
Verify integrity of application files... Choice.
Let it do its thing.
That will get everything back to stock install.
NOTE:
Might want to back up your entitybank and script files if you have done any custom work.
Doing this will make it as it was when installed.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.
