[HELP] how can I restart my computer so it performs like it use to

Before you tell me to system restore, for some reason my computer cant do it no matter what. Ive tried different dates and everything. Someone told me my system restore point are damaged maybe? MY computer recently had a virus which messed up my internet connection and other options..

So its come down to this:
Is there anyway I can just delete everything on my comp and start it back to normal like the first day I got it?

I was thinking to make another Admin Account on my computer and just delete the other one that's damaged, and start from scratch. What is an easy method to save some important files before I delete the account?

Or is there a different way I can do this without having to delete my first admin account?

I have a HP pavilion XP sp2 desktop, which I got about 2-3 years ago so its still somewhat up to date

But yeah, thanks in advance for taking the time to read my problem and questions. Any help would be appreciated!

Have you tried a registry cleaner on it?

Personal recommendation: Registry Mechanic from PC Tools.

I think a sc. "repair installation" is the easiest way out of this.

Then you wont loose anything but the Windows updates. If you have any non WHQL signed drivers installed that you know of? Unistall them first. Or you may have some problems during the repair.

Here is a repair guide:

http://michaelstevenstech.com/XPrepairinstall.htm