Anyone who’s ever worked the help desk knows how easily people can forget their account credentials. In a managed environment, it just takes a couple of mouse clicks and the problem is solved. In a workgroup where machines were set up independently (and often by their users), locking out the only administrative user could mean wasting hours migrating user data to an entirely new installation.

A complicated problem, though, doesn’t always require a complicated solution. With an OS X install disk (like the one that comes with each Macintosh computer) you can easily reset any account password.

Now restart the computer holding down the “C” key with the install disk in the optical drive. When the installer starts, choose your language, and you’ll proceed to the welcome dialog. Go to the “Utilities” menu at the top of the screen, and choose Reset Password. At the top of the window, select the boot volume, then the appropriate user from the pulldown menu. Enter a new password, click “Save”, then restart.

Be careful with this method if File Vault, the OS X encrypted home directory system, is enabled. Preventing easy data access is what it’s designed to do, and without the master password (set when File Vault is first set up) you’ll be locked out of the user’s files forever.

Once you’ve logged back in with your new password, you’ll want to remove the user’s old “login” keychain, since without the original password it can’t be unlocked and used. Open Keychain Access (in the “Utilities” folder), click “Show Keychains” from the bottom left of the window, and choose “Delete Keychain login” from the “File” menu. Then “Delete References & Files” when asked, leaving the account ready for use once again.