Audio issues with Zoom

I am running Zoom on Window 11 on an HP Laptop with a built-in microphone. Suddenly, other people cannot hear me on Zoom.  I have checked microphone permissions for apps and desktop apps  in Zoom and they are OK. 

Today I reinstalled Zoom on the laptop once again and I find going into Zoom application/setting/audio that the Test Mic is greyed out - I can't test it

When I do my own test Zoom meeting I try to join with Computer audio I get a red message saying "Leave Computer Audio" and a message below saying "Failed to detect your microphone. Please make sure your microphone is properly connected."

What do I do now?