Go to Settings > Privacy > Microphone.
At the top of the window, check that it says “Microphone access for this device is on.”
If Windows says microphone access is off, click the “Change” button and set it to “On.”
Wipe the surface of the keyboard with liquid - absorbent towel and dry it with a hair dryer for a while.
It is recommended to reinstall the system or send it directly to the repair station.