-Shut down the computer.
-Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously.
-Turn on the computer.
-Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
-Hold the keys down until the computer restarts and you hear the startup sound for the 2nd time.
-Release the keys and let your system boot up.
Reset the SMC of a MacBook or MacBook Pro’s with detachable batteries:
* Shutdown the MacBook/Pro and remove the battery * Disconnect the power adapter, hold the Power Key for 10 seconds * Release the power key and reconnect your battery and power adapter * Turn your Mac on * Let boot as usual.
Reset SMC of a MacBook or MacBook Pro’s with an internal battery:
* Shutdown your MacBook/Pro * Connect the power adapter to your Mac * On the MacBook/Pro’s keyboard, hold down the Shift+Control+Option keys and the Power button at the same time * Release all keys and the power button at the same time * Boot your Mac as usual
-Find out whether the battery on your Apple portable has power.