First of all how old is the monitor, and do you leave it on all the time? Mine started doing that, plus when it worked it looked curved on the sides,,,,,,, monitors do wear out,,,,,, i picked up my current one at a pawn shop, for 10 dollars,,,,,
suggestion- as stated above, try that monitor on another computer, or borrow a monitor and try on yours, that will help you determine if its a computer problem or a monitor problem,,,,,, i would imagine its about as cheap to get a new one, as repair one