|Sounds like you may have uninstalled your graphic driver?|
You really shouldn't uninstall things willy-nilly. Not a good practice for what you describe. You should probably ask for help when your computer runs slow and describe your running processes etc. when asked and you would probably be in better shape presently.
You will have to find out what graphic driver your system needs and download and install it.
And yes, it is possible that you have picked up a virus, but it would probably manifest itself in other ways than just making things on screen appear too big.
"Doin' right ain't got no end." Cap'n Red Legs