This article is good for those who lost their admin password and MAC OS disk. Still there is a way to create a new admin  account in MAC OS and the bad part is that your old files will not be accessible with new account.
Follow these steps to reset your OS X password without an OS X CD and to create a new admin account. As first step you have to enter terminal to create admin account.
1. Reboot
2. Hold apple key + s key down after you hear the chime. (command + s keys on newer Macs)
3. When you get text prompt enter in these terminal commands to create a brand new admin account (hitting return after each line).
mount -uw /
rm /var/db/.AppleSetupDone
shutdown -h now
4. After rebooting you should have a brand new admin account. When you login as the new admin you can simply delete the old one and you are good to go.