Method 1
Boot up with DOS and delete the sam.exe and sam.log files from
C:\Windows\system32\config
in your hard drive.
Now when you boot up in NT the password on your built-in administrator account which will be blank (i.e No password). This solution works only if your hard drive is FAT kind.
Method 2
Put your hard disk of your computer in any other pc.
Boot that computer and use your hard disk as a secondary hard disk (Don't boot as primary
hard disk ).
Then open that drive in which the victim’s window (or your window) is installed.
Go to location
C:\Windows\system32\config
Delete SAM.exe and SAM.log
Now remove hard disk and put in your computer.
Now boot your computer.
How to "Delete Administrator Password" without any software