How to repair Windows XP

First you must make sure your CD/DVD drive is the first boot device.
This can be done on system boot up by entering the CMOS setup by pressing the key shown( usually a message saying press xxx to enter setup) and changing the first boot device to CD/DVD drive then save and exit.

Make sure your Windows XP CD is in the drive ,when the Press any key to boot from CD message is displayed you must press a key on the keyboard to boot from the CD.
The CD will load system files and when done the main blue screen will appear with three options choose the one that says To setup Windows XP now by pressing the ENTER key.
Do not choose the option to Repair windows by pressing the R key as that will take you to the Recovery Console.
After pressing ENTER you will be shown the Windows XP Licensing Agreement press F8 to accept and continue.
On the next screen you will see your current installation and you will have the option to Repair Windows by pressing the R key ,press it and windows will start the repair process.
Follow the instructions and enter the required details when prompted.

You must keep your CD in the drive until the process is complete.
Some installations require you to input your 25 character Windows XP product key (this is usually stuck to your computer box or under your laptop).