How to change a Windows XP/NT/2000 password without knowing the original password

From ArticleWorld

This guide will show you how to change the password of a Windows computer if you do not know the old one. Although this is normally associated with cracking, it is perfectly legal if the reasons are legitimate. You will sometimes find yourself in such a case, either because you have forgotten your password, or because you have received a computer by donation and the donor has not given you the Administrator password. Do note that if your reasons are not legitimate, this is considered an infraction.

What you need

You will need a 1.44 MB, formatted floppy disk, or a CD if you prefer. If you are using the floppy disk, you will need this boot disk image: http://home.eunet.no/~pnordahl/ntpasswd/bd050303.zip . If you prefer the CD, download this image: http://home.eunet.no/~pnordahl/ntpasswd/cd050303.zip

How to do it

1. Download any of the images above and unzip it to a folder on your computer.
2. If you picked the CD image, just burn the .iso file to a CD. If you picked the floppy image, open the file called "install" and follow the instructions. At a certain point, it will ask you to supply a floppy disk.
3. After you have finished the above step and successfully wrote the CD or the floppy disk, reboot. You may need to change your computer's BIOS settings so that the system will boot from the floppy or CD instead of the hard drive. Refer to your motherboard's manual for instructions on this.
4. If booting went well, you will see a list of partitions. Choose the one on which Windows is installed.
5. Now choose the user account whose password you want to change. You can also remove the password, or enable some disabled accounts. You can reboot at any time if you do not want to continue. You can turn off (not: not reboot, but power off and power on again) your computer if you encounter errors or you did something wrong.
6. After you are happy with what you have done, reboot.

Notes

It is usually more efficient to simply remove the password instead of changing it. Removing the password will work almost always, while changing the password may fail sometimes.

You should also note that the program uses some cryptographic code which may be illegal to import or export to or from your country of residence. You should check the status of cryptographic codes in your local laws.