This article will walk you through how to reset your user password in Mac OS X.
1. Enter the Recovery Partition on your Mac. You can do this by restarting your Mac and holding down Command (⌘) + R. Keep holding down until the Mac boots into the Recovery Partition.
2. Click on Utilities in the Menu bar and select Terminal.
3. In the Terminal window, type 'resetpassword' and hit Enter.
4. A new window will pop up with your Macintosh HD. Click on your partition at the top of the window and select your user account from the Select User Account drop down menu.
5. Enter and reenter your new password and click Save.
6. After saving, click on the Apple icon in the menu bar and select Restart. You should now be able to login to your user account.