Shut down your Mac. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. Turn on your Mac. (This step requires some dexterity!) Press and hold the Command-Option-P-R keys immediately after you hear the startup sound. Continue to hold the keys down until you hear the startup sound twice. After the second […]

More

Shut down the computer. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time. Release all the keys and the power button at the same time. Press […]

More