I hope this will never happen to you. But if you ever forgot your root password, then follow these steps to reset it. I cannot guarantee this method will work for all versions of osx, but it worked for me on my mac mini 1.5 GHz model at least.
- Hold Apple+S when booting, you will then enter the single user mode
- Run “/sbin/mount -uw /”. If you read through all the bootup comments it’s somewhere in there. It basically enables you to make changes to your hard drive.
- Run “passwd”. Then put in your new root password twice.
- Run “exit”. The reboot process should begin. You are done!