I had to use this one this morning for a client that forgot their mac account password. This is really easy and very powerful, just so long as you have physical access. It requires no discs or "hacks" and it is built right into mac which makes it that much more reliable
Here's how to reset your OS X password without an OS X CD.
the Working solution for me was to create a new admin
you can create new admin like this by deleting a specific file.
You need to enter terminal and create a new admin account:
2. Hold apple key + s key down after you hear the chime.
(command + s keys on newer Macs)
3. When you get text prompt enter in these terminal commands to create a brand new admin account (hitting return after each line):
mount -uw /
shutdown -h now
4. After rebooting you should have a brand new admin account. It will take you through a new quick setup and once in you can do what ever you like to any account. Including resetting passwords.
Merry Christmas everyone & stay safe on the roads!!