Resetting OS X Password Without Having The Installation Disc?
Recovery HD

The simplest way may be to use the Recovery HD.


Boot into the Recovery HD (hold ⌥ alt/option at boot and select the Recovery HD).
Once it has booted, click Utilities, then Terminal.
Type resetpassword then ↩ enter.
Follow the instructions.


Restarting Setup Assistant

In addition to using the Recovery HD, you can also restart the Setup Assistant, create a new Administrator account, then use that account to reset the password to the original account.

You can restart the Setup Assistant by performing the following:


Boot into Single User Mode (hold ⌘ cmd + S at boot).
Mount the drive by typing /sbin/mount -uw / then ↩ enter.
Remove the Apple Setup Done file by typing rm /var/db/.AppleSetupDone then ↩ enter.
Reboot by typing reboot then ↩ enter.
Continue setup, making sure not to transfer data.
Setup a new administrator account. You can use this account to reset the password to the original account (through System Preferences → Users &amp; Groups).




The new account can then be deleted once the original account has been recovered.