The speaker icon in the Taskbar’s notification area may appear with a red cross. When you hover the mouse pointer, it may say, “The Audio Service is not running.”
Clicking the speaker icon may launch the Get Help or the audio troubleshooter. This happens if the Windows Audio service is turned off. As a result, there will be no sound output in your device.

Launching the Volume Mixer by running Sndvol.exe would show the following error:
No audio device is installed
