Check if the HDMI or VGA connection from your computer to your projector is properly connected.
Power cycle or restart the devices and then turn them back on in case it’s a VGA connection and you can’t plug & play the projector with your computer.
If your projector isn’t turning on when you push the power button, do the following.
Check the control panel if it has a status or indicator LED light. Refer to your user’s manual or the maker’s website for explanations or solutions if the light is on.
Check the input. You might have the incorrect input. Most projectors have multiple inputs for VGA or HDMI or HDMI1 and HDMI2 or Computer 1 and Computer 2 and so forth. Switch from input to input using the input button on the projector.
You can also hit the FN key and a function button with a monitor icon on your laptop to get the picture to project from your projector. It varies from laptop to laptop.
The function key can read CRT, LCD, or have the aforementioned monitor or group of monitors icon. Press to obtain the image from your projector.