Why do both screens go black when trying to duplicate?

[Windows Central Question]

Hi all,

I am attempting to duplicate my computer screen onto my television. I have been able to duplicate or extend my computer screen with Windows 10 before but all of a sudden the function no longer works. I think I had selected second screen only when playing around and I am suspecting when I selected this it somehow triggered this problem. I have not been using any cables and have been able to connect seamlessly over wifi.

 

[Arvind Kumar117]

Did you try using Win+P for switching, And which build is you OS