Boot up with DOS and delete the sam.exe and sam.log files from Windows\system32\config in your hard drive. Now when you boot up in NT the password on your built-in administrator account will be blank (No password). This solution works only if your hard drive is FAT.
1. Put your hard disk of your computer in any other pc .
2. Boot that computer and use your hard disk as a secondary hard disk(i.e. don’t boot as primary hard disk ).
3. Then open that drive in which the victim’s window(or your window) is installed.
4. Go to location windows->system32->config
5. And delete SAM.exe and SAM.log file
7. Now remove victim’s hard disk(your hard disk) and put in your computer.8. And boot your computer:-)