How To Change Windows Admin Password Using Guest Account
To change the password you need to login first. Use any Gues Account to login to Windows or
if your computer doesn't have a guest account you can use KON Boot method to get into the administrator account without knowing the actual password.
After logging in follow these steps to change the password:
Step 1:Right-click on My Computer and select Manage.
Step 2:From the left side bar click on Global Users and Groups.
Step 3:Double-click on Users.
Step 4:Righ-click on Administrator and select Set Password....
Step 5:Click Proceed to continue.
Step 6:Enter New password and click OK. That's It!!
I have checked this trick on Windows XP yet, i'm not sure about newer Windows, try it and let me know if it worked for you :)
Also check my previous post: How To Hack Windows Admin Account Using KON-Boot