If you have a XP disc do a repair of XP
How to repair Windows XP/2000 if you are unable to boot into Windows
You first have to configure your computer to boot from the CD-ROM drive.
You need to enter your BIOS menu and change the boot setting to boot from the CD-ROM drive
as the first device and the hard drive as the second boot device
Then insert your Windows XP Setup CD, and restart your computer.
When prompted press any key to start your computer from the Windows XP CD.
When prompted press ENTER, and then press ENTER displayed on the Welcome to Setup
Do not choose to use the Recovery Console to repair your installation of Windows XP.
Press F8 to agree to the Windows XP Licensing Agreement.
Make sure that your current installation of Windows XP is selected in the box, and then press R
to repair Windows XP.
Follow the instructions on the screen to complete Setup.
Warning: you should always backup any data or settings which you do not want to lose.
This type of repair should not lose any data however; you may find that some settings have
changed once you have finished the reinsta