If you can’t see your Mac desktop on an external display
If you connected your Mac notebook to a display or TV but can’t see your Mac desktop on the display, try the steps below.
Close the lid on your Mac notebook to put it to sleep.
Connect the power adapter to your Mac and a power outlet.
Reconnect your Mac to an external display.
Connect a USB keyboard, mouse or trackpad to your Mac.
If you’re using a wireless keyboard, mouse or trackpad, make sure it’s turned on.
Wait a few seconds, then press any key on the external keyboard, or use the mouse or trackpad, to wake your Mac.
If your wireless keyboard, mouse or trackpad isn’t connected (paired) with your Mac, Bluetooth Setup Assistant opens so you can connect them.