Any way to help?

I tried to change my resolution in game yesterday because this computer is stupid. it only goes in one format and everything is slightly blurry. anyways i change it to the exact resolution this screen should be able to handle and i got a notification saying "incorrect format" on my T.V. screen, which is what im hooked up to, and the whole game went black, but i could still hear everything, so i decieded this morning to re-install LoL and the resolution stayed, and i still can't see anything and now i am 99% sure i'm on leaver buster because i have to restart my computer other wise i'd be stuck there looking at a black screen forever. is there anyway to fix this?