It’s actually possible to reset a Windows password with nothing more than your Windows installation disk and a few bits of clever command line magic.
First, boot from your Vista or Windows 7 installation disk – whichever matches your installed OS.
Once you are up into the GUI click the option link titled Repair your computer.
Step through the brief series of questions and prompts until you are present an option to open a Command Prompt.
The password reset leverages a pseudo exploit of the sticky keys executable sethc.exe. Just to be safe let’s first make a copy of the original file with copy c:\windows\system32\sethc.exe c:\
With a suitable backup in place overwrite sethc.exe with the Command Prompt program cmd.exe by issuing the command copy c:\windows\system32\cmd.exe c:\windows\system32\sethc.exe
Reboot your computer.
Once you are staring at the familiar Windows login screen invoke the Sticky Keys program by hitting the Shift key 5 times. Windows will instead open an Administrator Command Prompt.
In the Command Prompt window issue the command net user <username> <mynewpassword> to reset the password on the specified account.
Now, close the window and login with your new password.
Finally, you should restore the sethc.exe that you over-wrote previously by executing copy c:\sethc.exe c:\windows\system32\sethc.exe in an Administrator Command Prompt.
