i would like to know how to set my windows xp to factory settings i tapped the f-10 do i need to hold down the f-10 please help me

What you're talking about is a system restoration/recovery, which usually destroys your personal data as well. Be aware of that.

Tapping F10 on boot -- for some computers -- will bring up the system recovery utility where you can reinstall Windows with all of its factory pre-installed stuff and settings. This is not part of Windows, but provided by your manufacturer to 'clean' your computer of any changes made since it was shipped, including your personal stuff.

If it prompts you to press F10, tapping it repeatedly should work. You need to do it during the BIOS (Usually a few seconds before the Windows logo appears). If it doesn't work, there may be an issue with your system recovery partition. If you've had some major work done to your computer like reinstalling or upgrading Windows, hard drive replacement etc.. Then your system recovery partition may not work properly or even exist anymore.

And no, holding it will not be necessary.