How to reset windows password

What to do if you forget your Windows
password
Applies to Windows Vista
If you've forgotten your Windows password and you're on a
domain, you should contact your system administrator to
reset your password. If you're not on a domain, you can reset
your password by using a password reset disk or by using an
administrator account.
If you forget the administrator password and don't have a
password reset disk or another administrator account, you
won't be able to reset the password. If there are no other user
accounts on the computer, you won't be able to log on to
Windows and will need to re-install Windows.