The admin password is of cardinal importance when trying to make operational changes in a computer, as it provides users with access to the administrative account. If the user forgets the password and the installation CD of OS X is also missing, then he/she faces a problem. Luckily though, in the case of Mac OS X, the operating system for Apple products, this problem has an easy solution. One simply has to enter the terminal and create a new admin account and delete the old one. Once the system is rebooted, the Mac OS admin account will work seemlessly even without the OS X CD.
I forgot my admin password and I lost my OS X disk! How can I reset the admin password?
Here is the best and easiest way to reset your OS X password without an OS X CD.
The solution for me was to create a new admin; you can create a new admin like this by deleting a specific file.You need to open terminal and create an administrator account:
Hold simultaneously Apple + s down after you hear the chime.
When you get the command prompt enter the following commands to create a new account as administrator (hitting return after each line):
mount -uw /
shutdown -h now
After rebooting you might have a brand new admin account. When you login as the new admin you may delete the old one and you're good to go again!
Please note that Apple stores won't reset it for you. Computer shops may charge you $50 to $200 to try and reinstall the Mac and end up failing anyway.