Here’s the link to download Offline NT Password and Registry Editor and instruction on how to use it.
If your computer allows booting from floppy disk or cdrom, your Windows’ password can also be reset using some boot disk or CD like that one. You should disable booting from any disk, like floppy, cdrom, flash drive. etc. except for hard drive in BIOS setting if your computer is public computer or you don’t want others to reset your password.
If you download this iso or floppy image to another computer, burn or create the diskette and then boot the found machine to this disk you will get a new console to blow away the password.
And here is a link to a video doing the entire process.
That should do it for you and you should be able to not only get into and use that computer but see what ever was on the machine before! Let me know how it goes.
Another link to download Offline NT Password and Registry Editor
Simple answer? You will need to do a clean intall of the operating system. You did not say what version of Windows it is using. That could make a difference too. Please include those details. Thanks.