How to Reinstall All Windows XP Updates

1). Disable your Internet connection by unplugging your Ethernet connection or turning off your wireless device.
2). Click on "Start," then "Control Panel." Click on "Classic View" in the left column, if applicable.
3). Double-click "Add/Remove Programs."
4). Click on the "Show Updates" checkbox. Select the first service pack listed, then click on "Remove." Click on "Finish" to restart the computer.
5). Repeat for each service pack and for any stand-alone Windows Updates listed.
6). Reconnect to the Internet and open Internet Explorer. Click on "Tools," then "Windows Update." Reinstall all service packs and additional security updates. Restart the computer when prompted.