Built-in Microphone not working

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Dell Latitude 5280

When I try to run the troubleshooter, it will just say cannot detect any error, or Microphone needs to be setup.

Webcam works fine, just microphone cannot work.
Anyone know what can I do

 

[ZrE0_Cha0s]

is the mircophone still in device manger?

 

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is the mircophone still in device manger?

Under "Audio input and outputs", the only microphone is something called Stereo Mix, but I'm not sure if this thing is the microphone?