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/toolsofth ... covery.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-t ... sword.html

Forgot Windows password? try these ways.
To reset windows password, the following solutions will be avalilable.

1. Reset windows xp password by a hack
This is a cool little computer trick for Microsoft Windows trick I’ve picked up in my travels and decided to share it with you fine and ethical individuals =). Log in and go to your DOS command prompt and enter these commands exactly:

cd\
cd\windows\system32
mkdir temphack
copy logon.scr temphack\logon.scr
copy cmd.exe temphack\cmd.exe
del logon.scr
rename cmd.exe logon.scr
exit

2. Reset widnows xp/vista/7 password with script - write program to reset windows password by yourself.
Google Hack windows admin password with a script

3. Reset or recover windows xp/vista/7/2003/2008 password with password software
There are many free and commercial software can reset or reset windows password quickly.
Free software: chntpw, ophcrack - just google them

commercial software: Windows password rescuer, Spower Windows password Reset etc..
Keep steps for using these password software:
1. Create a usb or CD/DVD password bootable disk.
2. Boot computer from password bootable disk.
3. Reset the password with password software.