Now for reasons I won’t delve into I have an EFI Firmware password set on my Mac. I presume if your reading this article your the same. The EFI firmware password essentially stops you doing any of the important key combinations at boot, resetting PRAM/NVRAM, single user mode the whole shebang. Now this is useful in many many circumstances except when your screwed like I was. Essentially when I thought I was resetting my PRAM and NVRAM I was doing absolutely nothing. If your as screwed as I was and cannot get to a DVD to boot OR you have forgotten your password there is only one way around it.
1.Add or remove a stick of ram. Obviously if you have one stick in, add one and if you have two in remove one.
2.Power on the mac and immediately press and hold command-option-P-R.
3.The system will restart with the ‘bong noise’, allow it to do this 3 times. On the third ‘bong’ you can let go of the keys.
4.The machine will now boot with a cleared password and reset PRAM/NVRAM.
5.You can shut down the machine and replace the original ram configuration.