Get A Computer With No Credit How To Get A Virus Off Of My Computer When The Virus Won't Let Me Do Anything On My Computer?

How to get a virus off of my computer when the virus won't let me do anything on my computer? - get a computer with no credit

I have a virus on my computer and I'm not sure how to remove it. I can not run McAfee security or restart the computer to another date. Every time I try to do everything that the virus from the farm. Oh, and I'm running Windows Vista. No idea how to fix the problem?