Why does my laptop monitor go blank when I plug in an external monitor?

Episode 1322 (42:17)

Tom from Bozeman, MT

Tom's laptop monitor goes blank when he plugs in an external monitor. Leo says to look into the display settings to make sure "extend" is selected. Leo suspects physical damage to the Dell Laptop. One thing to test is to try Windows Key + P. This will open the project side bar and see how the external screen is handled. It could be that second screen only has been selected. If it has, Windows has turned off the laptop screen.