Forgot my Windows Admin Password???

How can I gain access to a Windows 2000/XP/NT computer if I forgot the administrator's password? How can I reset the administrator's password if I forgot it?

• Free Tools
  Free Windows password-cracking tools are usually Linux boot disks that have NT file system drivers and software that will read the registry and rewrite the password hashes for any account including the Administrators. This process requires physical access to the console and an available floppy drive but it works like a charm! I've done it myself several times with no glitch or problem whatsoever.
  Beware!!! Resetting a user's or administrator's password on some systems (like Windows XP) might cause data loss, especially EFS-encrypted files and saved passwords from within Internet Explorer. To protect yourself against EFS-encrypted files loss you should always export your Private and Public key, along with the keys for the Recovery Agent user. Please read more about EFS on my What's EFS? page.
  Here are three of these free tools:
  Petter Nordahl-Hagen's Offline NT Password & Registry Editor
  Openwall's John the Ripper
  EBCD – Emergency Boot CD
  Austrumi