To repair an installation of Windows XP you will need your Windows XP - Installation Disk. Place this disk into your CD/DVD Drive and restart your computer.
Now you will need to set you computer to boot from the CD/DVD drive. Please see the How To Boot From The CD/DVD Drive guide on how to go about this.
The following is how to repair an installation of Windows XP...
When you boot from the CD you will have to to Press any key to boot from CD
Now your computer's hardware configuration will be inspected.\
The Windows Setup will now load all files that are needed.
Now as we are Repairing Windows XP press Enter
Now you will have to accept a License Agreement to use Windows XP, so press F8 to Accept.
The Windows Setup will then look for previous versions of Windows.
Now as we are repairing a Windows XP installation press R
Now files should be copied to the Windows XP installation folders.
Your computer will now be restarted in 15 seconds.
However by pressing ENTER you can force a restart.
Once the computer has restarted Windows XP will continue to install. Once this installation has completed you should then install any Service Packs or Windows Updates. You should also find that your documents and applications have remained and you can continue to use your computer as normal.
This is all that is required to repair an installation of Windows XP. Repairing an installation is a lot less time consuming then reformatting and reinstalling. You also have the benefit that you do not need to install any applications and your documents will remain where they were. If you find that you are experiencing problems that are proving difficult to solve you might want to consider a repair installation.