I'm sorry about the issue. Can you please click on the Apple logo / menu at the top, then click on About this Mac..., then tell me your Mac OS X version, such as 10.6, 10.7, 10.8, etc.?Please reply at the box below. Thank you,
- Press at the same time the 3 keys on the keyboard Control + Shift + Eject, then it will turn off the monitor.
- If that does not work, press at the same time these 3 things: Control + Shift + Power button, then it will turn off the monitor.
- If it still does not work, click on the Apple logo / menu at the top, then click on System Preferences, then open Energy Saver if available, then Set Display Sleep.
Please type at the box below, then click on the Send button below to communicate with me, so I can help further. Thank you,