I just want my screen to be back to normal!!!?

I have tried everything people told me on here. I am at my witts end. I downloaded some stuff for this game and It got messed up. Now, its all messed up, and I deleted allt the quake stuff. I can't acces my graphic card it keeps saying this is not running. Everything is bright, not because of the monitor. and nothing is coming in right. I am getting really frustrated.