There are a number of different causes for the black screen error and you may need to try several of these possible solutions before you find one that works for your MacBook Pro.
Apple has issued a statement regarding a known problem with certain graphics cards. This affects systems built in 2007 and 2008. If your MacBook Pro falls into this category, Apple may provide a repair free of charge. For more information, follow the link below to the Apple website.
Trying to fix the problem
Step 1: Hold down the Command, Control and Eject keys; this should force your machine to reboot. You can also try a forced shutdown by holding down the power button for several seconds.
Step 2: Some users report putting the MacBook Pro into sleep mode can stop the problem. The easiest way to do this is to unplug the power, close the case completely, wait until the sleep light comes on and then reopen it. Alternatively, press the power button once and then the S key. Pressing the power button under normal circumstances brings up the list of shutdown options - pressing S in this mode is the shortcut to sleep mode.
Step 3: Adjusting the screen brightness options (F2 or Fn + F2) has been known to bring the image back in some circumstances.
Step 4: As the MacBook Pro boots up, hold down the Apple key, Option, P and R. This resets a number of system settings and can get the computer running again.
Step 5: This issue can occasionally be caused by external devices connected to your computer. Disconnect all devices and try restarting again. If this works, reconnect them one by one to find which one is faulty or causing the problem. This can also be caused by Bluetooth devices waking the computer when in sleep mode. Restarting the computer and disabling this setting can rectify this.
If you manage to restart your MacBook Pro
We recommend you backup your computer to an external source as soon as possible. Although this is often a one-off crash, it may be a symptom of a component starting to fail.
If you can't restart your MacBook Pro
If the computer will not start at all, it's likely to be a hardware issue; this will need diagnosis and repair by a specialist.