bro doing system restore will not completely remove viruses but the previous suggestion to pull up system restore is correct. For best result run system restore in safe mode. Once in safe mode go to start>all programs>accessories>system tools>system restore. Sometimes it will take 3-5 minutes before system restore window shows up.
system recovery (if you are using HP pc/laptop) will erase everything in the pc and will bring it back to its factory configuration. after that you have to reinstall the drivers for your external devices and install application programs.
you can access system recovery by going to start>all programs>pc help & tools>recovery manager (if you are using HP pc)