If you can’t see your Mac desktop on an external display
If you connected your portable Mac to a display or TV but can’t see your Mac desktop on the display, try the steps below.
Close the lid on your portable Mac 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.