How to Reset a Windows NT 4.0 Passwordby Dave Wilson
Windows NT 4.0 is designed to allow only users that present proper credentials (for accounts configured locally on the computer or domain accounts) to log into the computer. Fortunately, forgetting or misplacing the account password (especially the administrator account password) can be resolved quickly.
Install a second copy of Windows NT 4.0 onto free space located on the computer containing the account that requires a password reset.
Boot the computer into the second Windows NT 4.0 installation and log into the Windows NT 4.0 computer using the administrator account credentials for the second Windows NT 4.0 installation.
Double click "My Computer" on the computer desktop. Navigate to the "\Winnt System32" directory of the original Windows NT 4.0 installation.
Click once to select the "Login.scr" file located in the System32 directory, and then press the "F2" key to activate editing the file name. Type "loginold.scr" for the file name and press the "Enter" key.
Right click on the "cmd.exe" file located in the System32 directory and click "Copy" in the menu that appears. Right click on the PC desktop, click "Paste," and a copy of the "cmd.exe" file should appear.
Click on the "cmd.exe" file located on the desktop, press the "F2" key and then in the file name editing box type "Login.scr." Press the "Enter" key.
Right click on the renamed "cmd.exe" file that is on the desktop of the PC and click "Cut." Right click on empty space in the "System32" directory window that is still open and click "Paste" in the menu that appears.
Reboot the computer into the original Windows NT 4.0 installation by selecting the original installation in the boot up menu. Wait for the screen saver timeout to be triggered. A command prompt window will appear when the screen saver timeout occurs.
Type "net user account new_password," substituting "account" with the name of the account for which the password must be reset, and substituting "new_password" with a replacement password for the account. The account password has now been reset.
Delete the renamed "cmd.exe" file from the System32 directory, and rename the "loginold.scr" file in the System32 directory back to "Login.scr."