reset macbook pro admin password without installation disk

by Abhishek

Try this
Although there's no real way to recover a lost root password, you can
change the root password even if you do not know the current one. You
must have physical access to the machine in order to accomplish this
task.

Click Restart at the login window
While the computer is restarting, hold down "Command-S" until you see text scrolling through the window.
This boots the computer into single user mode.

At the Localhost% prompt type:
/sbin/mount -uw //sbin/SystemStarter

You will then see various services starting up.

When the Localhost% prompt reappears, type:
passwd root

It will then ask you to type the new root password twice, so do so.

After entering the new password, type:
reboot

At the login window, enter username root wih the new password.

Once you are connected, you can use the Multiple Users application
(/Applications/Utilities) to change your normal user's password, or
create a new user account.

Good Luck! 😉