Ask Max: How to recover a monitor that has a resolution set out of range?
Well, now I've done it! I have a G4 dual 450 ("Sawtooth") and the matching graphite 17" Apple LCD display. I was fiddling around with screen resolution settings, and selected one too high for the display, which turned to black except for a message generated by the monitor itself saying something about "frequency out of range," or whatever. The problem is, it stays black and I can't see to adjust the settings down again. There are no other monitors in the house. Help! I don't know how to make things work again!
These things do happen from time to time and Apple has you covered. Built into every Mac is a general fix-all startup command that can get you out of monitor resolution errors and some startup errors. It is probably the first troubleshooting step you should use with any hardware problems on your Mac. It is called "Zapping the PRAM" and all it does is erases whatever your Mac had once known about its hardware configuration. Your Mac then searches for devices connected or installed and sets itself up in a compatible way.
With the computer off, hold down the "P," "R," "Option," and Command/Apple Keys. Continue to hold down those four keys and turn on your computer. Let your Mac chime four times before you release those keys. You should now be able to see your Mac booting up and things should start to look normal again. You may have to reset the date and other settings, but none of your data will be lost.