Hi.
For a long time, I connected a laptop HDMI output to the HDMI input of a television to watch overseas television channels like RT, NHK, BBC...
When the laptop sensed? the TV was connected, the audio on the laptop muted and the TV displayed the programming perfectly.
Now, only audio is reproduced at the TV. The video is not the same as on the laptop screen. The Windows 10 splash screen is what shows up together with the streaming audio. Tried other HDMI inputs; same.
No changes done to the laptop; it is a dedicated unit only to watch streamed programs. What went bananas ? How to fix ?

Is there a Microsoft site that will diagnose/update/install automatically whatever is bad/missing ?

 

There is generally a function button to select what is shown on the second screen. On this machine it is F9 + function button. YMMV.

 

Thank you, Albert. F8 alone without the Fn key did it on mine! Gave me 5 options to choose Solved.