Windows 7 /8 admin password change using Guest Account

Step-1 Go to C:/windows/system32.
Step-2 Copy cmd.exe and paste it on desktop.
Step-3 Rename cmd.exe to sethc.exe.

Step-4 Copy the new sethc.exe to system 32,
           when windows asks for overwriting the file,then click yes.
Step-5 Now Log out from your guest account and at the user select window,
            press shift key 5 times.
Step-6 Instead of Sticky Key confirmation dialog,command prompt with
             full administrator privileges will open.
Step-7 Now type “ NET USER ADMINISTRATOR "new pass" can be any password you
            like and press enter.
Step-8 You will see “ The Command completed successfully” and then
            exit the command prompt and login into administrator with your
             new password.