There are two ways to do this.
1. Boot up pc with command prompt.
2. Change your directory into c:\windows\system32\config
3. Now delete “sam.exe” and “sam.log” files
Write del sam.exe
And write del sam.log
4. Now boot pc with window and password will be blank.
Note:- this will work only if the hard drive is of FAT type.
1. Remove the hard disk from the cpu.
2. Attach this hard disk with another pc. And make this hard disk secondary.
3. Now boot pc with window.
4. Open the drive in which window of secondary hard disk Is installed.
5. Open windows/system32/config.
6. Delete sam.exe and sam.log.
7. Now remove secondary hard disk and attach this with its own cpu.