In your start menu under All Programs, wasn't there a restore program there? Accessories and system tools? You could have picked the point of a few days ago and it would have restored the computer to that point.

Do you update all your definitions and updates every day & run all your scans every day? What softwares do you use? I have AVG free, Ad-Aware, Spyware Blaster, Spybot Search & Destroy, and SUPERAntiSpyware free. I've had them for years and don't have that many problems. I try to download all my software from http://download.cnet.com/windows/