Why not try Windows Password Recovery Tool? It is an easy-to-use tool designed for resetting Windows local account or domain passwords on any Windows system.Passwords can be reset in 3 minutes, no matter how long and complicated the password is.
Do you mean you forgot that user password? If not, you can change the user password by clicking start -> run -> control userpasswords, then choose the user you want to change the password.
But if you forgot that user password, a password reset disk and another user with administrator rights both can help you change the password. Then password reset software will be a second choice, such as Ophcrack, Rekeysoft Windows Password Recovery, all work efficiently to reset a lost user password.