Cannot connect to Microphone

When I open zoom and then test Speaker and Microphone, but the microphone did not work i.e. cannot record and playback. I am sure I choose the correct Mic and it works in other application such as voice recorder. I tried the following but the Mic does not work 

a) update the audio driver

b) delete the audio driver and re-install

c) reboot the notebook

d) uninstall zoom and re-install 

What else can do to fix the problem?