Resently I discovered that many people lost their Widows admin password include Windows 7/xp/vista/2000/2003/2008 especially on Yahoo Answers. I collected some available methods here, they may help someone.

If you lost your windows log on password, you can try these methods:

Method 1: Log on as admin to reset the password. When installing Windows, it automatically creates an account “Administrator” and the default password is blank. If you have previously created a password reset disk, you can use it to reset the password also.
http://support.microsoft.com/kb/321305 for more info.

Method 2: You can try free software such as Ophcrack,Offline NT Password & Registry Editor,PC Login Now and Kon-Boot. More details here: http://pcsupport.about.com/od/toolsofthetrade/tp/passrecovery.htm

Method 3: Use 3rd party password recovery tool (eg. Windows Password Rescuer and Windows password tools) to reset your windows password.This may be the easiest method. See help page at http://www.daossoft.com/documents/how-to-reset-window-2000-xp-vista-win7-password.html