Microsoft Windows XP uses a multi-user password logon system that enables users to have relative privacy. When these passwords are forgotten, using the system becomes impossible because that user cannot log on. Recovering the password for an account can be done in three main ways, and should take the average computer user about 20 minutes.
Use another account with administration rights to retrieve the lost password. Log on to the machine with the active account, then click on the "Start" menu and go to "Control Panel." In the Classic View, there will be an icon for User Accounts. Once in User Accounts, select the account with the lost password in the bottom of the window, and then click on "reset password." The prompt will ask for the password in two fields to ensure it is typed properly.
Reboot the computer into Safe Mode, then use the Administrator account to reset the password. To access the Boot Menu, press F8 repeatedly while the computer posts the boot data, before the Windows splash screen appears. If the splash screen appears then it is too late to access the Boot Menu, and the process must be repeated. Once in the menu, select "Safe Mode" from the list by pressing it's corresponding number. The computer will then display the normal user accounts, with an additional "Administrator" account at the top. By default, this account will not have a password, and will allow the user to enter Windows to recover the password of the forgotten account using Step 1.
Reinstall MS Windows XP from the original installation disc, and give the Administrator account a new password when prompted. Reboot the computer with the CD in the drive, and then select "boot from CD" when prompted. As the system loads the installer, it will detect the previous installation and ask to overwrite it or repair it. Select "Repair," and follow the prompts. It will ask for a new Administrator password, and this new password will allow the other user accounts to be modified as well.