If you have completely forgotten your password, you will be unable to reset it using the method outlined in Part One of our blog.
You should follow these steps to reset an Account Password for an Administrator on your Mac who has forgotten their password.
1) Start up from a Mac OS X Install disc (one whose version is closest to the version of Mac OS X installed). Usually, you can start from the disc by putting it in your computer, restarting, and holding the C key.
2) Choose a language, click the arrow button to continue.
3) Mac OS X v10.6 or later: Choose Password Reset from the Utilities menu.
Mac OS X v10.5 or v10.4: Choose Reset Password from the Utilities menu.
Mac OS X v10.3: Choose Reset Password from the Installer menu.
4) Select your Mac OS X hard disk volume.
5) Select the user name of your original administrator account. (Do not choose the Root user.)
6) Enter a new password and then click Save.
7) Click the red button in the upper left corner to quit the application.
8) Choose Quit Mac OS X Installer... from the Mac OS X Installer menu.
9) Click Restart.
Note Well: Resetting the password from the install disk in this way will allow you to access your computer using the Administrator account. You will, however, have lost access to all of the passwords that have been saved in your login Keychain. So, please use this with caution and only after all attempts at recovering your lost Account password have been tried.