Just had this with a client that I offer IT support for.
Just had a similar issue with this client that I offer IT support for.
It was weird 'cause their mic on their headset would work on other devices, but not on his. Making this a local problem with the laptop itself.
Used the usbc port with a usb hub, and low and behold the Microphone was now working. Which kinda pointed me to the internal usb controller.
So I opened up Device Manager as admin(devmgmt.msc in the search bar, right click and run as administrator) and uninstalled the usb controller. For me it was named: "Intel(R) USB 3.10 eXtensible Host Controller - 1.20 (Microsoft) - but to be on the safe side, uninstall everything under "Universal Serial Bus controllers"
Restart machine and the drivers will automatically get reinstalled, and hopefully with that your microphone on your headseat will start working as well.