This is an oldie and a goodie. Using NT Offline Password and Registry Editor from http://home.eunet.no/~pnordahl/ntpasswd/. This small boot floppy or cd is fantastic and I have been using it for many years to reset peoples forgotten local passwords on laptops and even to gain admin access of Windows XP.
After you create your Boot Floppy or Boot CD you are ready to restart your machine with the disk in the drive. If your machine does not automatically boot to the disk you may need to adjust your BIOS settings (if you can).
For most users you can hit the enter key for the defaults… Password Reset… Edit user data and passwords…
Now you will have a list of users to change… If you select the default it is the administrator. Change the password to * this will blank it out. Save your changes then reboot.
Log into windows with the administrator account and a blank password! If you see the home logon screen with no icon for the administrator simply click control alt delete and type in your credentials!