|I agree with omega it sounds like a possible mother board problem, but most times setup should be inaccessible too. What are your PC specs aside from the OS or Windows. |
As I understand is you don't won't to install windows you need to recover the one you already have or had on your computer and if it ran XP yesterday then why is it not working now.
Have you tried booting in safe mode, or one the other XP boot options, when booting up with out the cd press F8 right after the setup finishes Press F8 and make sure the XP cd isn't in your drive, that will get you to the XP boot options screen on older mother boards newer ones have a F12 boot options menu or something like that. There should also be an option to load you most recent settings that worked try that one first then if it fails try safe mode then sometimes a video driver conflict can cause windows XP not to load so try the enable VGA mode option if the others fail then if that works and windows boots look in your windows system devices and see if there is more than one video device installed like a add on card and a on board video device. If so remove one of them most likely the on board device and then restart windows in normal mode.
However if your key board locks up at the boot options screen and doesn't let you select anything that is another sign of mother board failure. That is if you know there is nothing wrong with your keyboard..