Double click on the speaker icon in the tray (bottom right of your desktop).
In the opened window volume control press the "settings" button in its upper part.
In the popup menu select "properties".
Put a mark next to "recording", check the checkbox next to "microphone" (if not necessary) and click OK.
You get the panel volume control input devices. On it, under the volume slider is the power button and mute. Turn it on.