Need to factory reset windows xp without disk

Restoring a computer to its original factory settings should be the last ditch effort in attempting to save a system that has been corrupted by viruses or defective programs. In the best case scenario, one would use the system restore CD that ships with new computers but often this CD is lost or the computer was purchased used. In this case, a factory settings restoration can still be performed by using the computer's "Advanced Boot" menu.
Restart the computer. Press the "F8" key after the computer reboots but before the "Windows" logo appears on the screen. You should now see the "Advanced Boot" menu. Scroll down through the menu options using the down arrow key. Stop when "Repair Your Computer" is highlighted and hit the "Enter" key. Select the language you wish to use and press the "Enter" key. Type in the computer's administrator ID and password. Press the "Enter" key. Scroll through the options using the down arrow key. Choose "Restore (name of computer manufacturer) Settings." Press the "Enter" key. Choose "Yes" when asked if you want to reformat the hard drive. Press the "Enter" key to begin the reformatting process. The process takes a few minutes, so be patient. Do not turn off the computer or attempt to stop the process after it has begun, or this may result in major damage to the hard drive. Choose "Finish" and press the "Enter" key to restart the computer. The computer will restart with the original factory settings.