Computer turns off by itself

I downloaded a desktop theme and then went into the control panel and double clicked the desktop themes icon and it said file not found and the same thing with the display icon. A friend of mine was there and he went int the setup screen and changed some of the settings, #5 and #6, to optimal performnce or something like that. Afterwards when he exited it he rebooted it and it started up like normal except where the desktop would normally come up the screen goes black and the computer and monitor shut themselves off. I went back into the setup screen and set all settings back to default and it still shuts itself off. Does anyone know what may be causing this???? I appreciate any suggestions

 

Oh boy - what fun. If you hadn't changed them back arbitrarily, you probably could have gone into the BIOS (thats what setup is) and restored the previous values if you knew exactly what he changed or what pages the changes were on. Unfortunately, you are now stuck with a lot of possibilities. Don't play around in there. Take your machine to a shop and give your friend the bill.