Why is my computer not displaying correctly on an external monitor connected with VGA?

What steps should I take to resolve this issue?

1. Make sure that the external monitor is plugged in.
2. If the external monitor is plugged in, reboot the computer.
3. Check the display settings.
4. Make sure that the correct input source is selected on the external monitor.
5. Try swapping the cable between the computer and the external monitor.
6. Check if the monitor works with another computer.