Windows Password Recovery Tool 3.0 is a bootable CD that enables you to reset local administrator and user passwords on Windows 7 / Vista / XP / NT / 2008 / 2003 / 2000.

Instantly gain access to your system if you have forgotten administrator password or user account has been locked out or disabled. Windows Password Recovery tool 3.0 is designed to help general users to remove forgotten Windows passwords. No need to reinstall Windows!

The only thing I can think of
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Is to use your password but I guess you have already done that one
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You can Google Search "Windows Password Recovery Tool 3.0"
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Depending the computer, it probably came with a CD or DVD for restoring the computer
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You boot from that disk and it will do the rest.

http://windowspasswordsrecovery.blogspot.com/