Press "Command+s" when booting up. A single user model is entered. The single user mode of MAC OS has access privileges (root access privilege) without requiring a root password (root password). A prompt like Dos #root > appears. Gradually enter the following command under #root>, note that spaces are case-sensitive
First step: Perform hard drive detection (read only), this step can be omitted
/sbin/fsck-y
Step two: Load the file system (read/write)
/sbin/mount-uaw
Step three: Delete OSX generated hidden files when initializing settings ". Applesetupdone"
rm/var/db/. Applesetupdone
Last Step: Restart
Reboot
A welcome screen similar to the installation appears after restarting the boot. Don't worry, things are not lost. Just like the first installation, re-establish a new Mac OS Administrator account. Then under the new Administrator open the system pre-account, open the bottom of the lock, ask the password, with the new administrator password to log in. will see at least two accounts, the new Administrator's account and the original account, point in the original account, select Password-change password. You don't have to have a previous Mac OS password to set up a new password directly. Click on the login option below (small house), check automatically login to the right, and select your original account in the dropdown menu. Reboot, you are done. At this point to crack Mac OS boot password work done.
Mac Apple Computer boot password forgot what to do