The easiest way to reset a forgotten Windows password is to use a previously created password-reset disk. You can create such a disk (on USB removable media or a floppy) within the Windows User Accounts menu by opening the Windows Control Panel, selecting User Accounts, and clicking Create a password reset disk in the left pane. You should take this step with a new PC; once you have the disk, you can insert it when starting the PC to cause Windows to display the 'Reset password' option at the login screen, allowing you to regain access to your system.
However, if you don’t have a password-reset disk and you need to reset your Windows password, I suggest using the following Sticky Keys trick.
Reset Your Windows Password Using the Command Prompt
1. Boot your computer using your Windows installation disc.
2. Wait for the setup files to load, and select your language. Click Next.
3. Click the Repair your computer link on the Install Windows screen.
4. Select the operating system to repair, and note the drive letter on which the OS is installed (it is probably C: or D:). Click Next.
5. Click Command Prompt at the bottom of the list of recovery tools.
Now you need to overwrite the Sticky Keys executable with the Command Prompt executable. Sticky Keys is an accessibility feature that allows a user to tap the Shift, Ctrl, Alt, or Windows key once to achieve the same effect as holding the key down. Ordinarily, tapping Shift five times activates Sticky Keys--but with this trick, you are going to make tapping Shift five times activate the Windows Command Prompt instead.
The instructions below use drive letter C: as an example. If your operating system is installed on another drive, replace C: with the appropriate drive letter.
1. In the Command Prompt window, type copy c:\windows\system32\sethc.exe c:\ and press Enter.
2. Type copy /y c:\windows\system32\cmd.exe c:\windows\system32\sethc.exe and press Enter.
3. Exit the Command Prompt and reboot the computer. At the login screen, tap Shift five times. The Command Prompt will pop up.
4. Type net user username password, replacing username with your username and password with a new password.
5. Exit the Command Prompt, and log in using your new password.
To prevent another user from exploiting the same trick to reset your password, you can restore Sticky Keys as follows:
1. Step through the instructions above to boot the PC using your Windows installation disc, open the recovery tools, and launch the Command Prompt.
2. Type copy /y c:\sethc.exe c:\windows\system32\sethc.exe and press Enter.
3. Exit the Command Prompt and reboot the computer. Pressing Shift five times will now activate Sticky Keys instead of the Command Prompt. Store your Windows installation disc in a secure location.
Caution: Resetting a password using the Sticky Keys trick means you will lose access to encrypted files, encrypted email messages, and stored passwords for Internet Explorer and network resources. Remember to back up your important data regularly.