Your Mac OS X password can be recovered using an administrator account, or by resetting the password to the administrator account.
I forgot my password to my Mac. What do I do?
There are two methods for recovering your password in Mac OS X – log in as the administrator and change your password, or use the system CD to gain access to the system.
If you forgot your own password but have access to the administrator account, you can use those administrative privileges to change your password. Visit this Apple support document titled “Changing or resetting an account password” and follow Apple’s directions. Once you’ve reset your password, make sure that this time it’s something you’re sure to remember.
You’ve forgotten the passwords to all of the user accounts on your system. You don’t even remember the Administrator password. End of the line, right? Wrong. If you have the Mac OS X CD that was used to install your system in the beginning, then you can use that CD to gain access to your Mac and change the password for any or all of the existing accounts. For detailed instructions on how to do this, visit the Apple support document titled “Changing your Administrator password“. After you’ve finished resetting your password or passwords, be sure to store away the system CD in a safe place since anyone who has it esentially has unrestricted access to your Mac.