Cannot Display This Video Mode

Hi, I messed up
i was messing around with the settings on my 8800GT when i decided to up the refreshj rate, just to check it out
once i did that it switched to a black screen in the middle it read

"Cannot Display This Video Mode"
"Optimum Resolution 1280x1024 60hz"

I tried to get in F2 setup and change the moniter settings, once completed it still didnt change anything and I just get this screen

I have no idea what to do