Not to discourage you by any means but there is a chance that you might have to reformat/reinstall.
In that case there is still a way to backup all your documents and files onto a external drive (without having to boot into corrupted windows). Go download any linux live CD distribution (fedora, Ubuntu, etc). Boot from the live CD, mount the windows C drive from the live CD. Connect a flash drive or usb external drive and copy all your files.
Go to this website and download Ultimate Boot CD for Windows. http://www.ubcd4win.com/
This program will create a bootable CD that will allow you to recover from almost any Windows XP failure.
If you want help doing this give me a shout through my website below. I'm bored right now anyway as all my customers are away Xmas shopping. :)
thanks for your info i downloaded the boot cd and have cd as 1st priority but nothing happened still asking for xp cd
Heres what to do to make the recovery CD
1-Install UBCD for windows onto your working system
2-Insert your windows XP CD into the cd drive on the working system and copy the I386 folder to your computer.
3-Remove the windows XP CD and insert a blank Writable CD
4-Run UBCD for Windows and set Source folder to point to the directory where you copied the windows files
5-select Burn to CD/DVD and make sure your drive is selected with the writable CD in place.
6- Select Build
Once you have built the CD then follow these steps.
1- Put the freshly created CD into your faulty system
2- Turn the system off then back on.
3-As the system starts up make sure you set it to boot from the CD (It should tell you on the POST(Power On Self Test=1st screen you see) screen something like press F12, F2, Del, F11 for setup options if can't see us tell us the make of your system?
4-Once your sure you have set it to boot from the CD watch out for any further messages as its starting up such as "press any key to boot from CD/DVD" as its asking you again to confirm that you want to boot from CD as opposed to the HD.
Voila you should be seeing a menu for UBCD - select Start UBCD for Windows and you should have full access to your system from the recovery CD.