Realtek HD microphone disappeared

Enable the mic where you disabled it, the bios or device manager. It should be reinstalled by Windows, but you may need to reinstall the Realtek hd controller again, which you can download from Dell.

Thanks for the above response; but the real answer exposes a truly dumb interface issue. When the mic is disabled, it's icon first greys out. However, on a return to the device manager, it's completely gone. In it's place is the text "no audio devices installed". Still sounds like my respondent has it right, doesn't it? Well, not exactly. If you place your pointer over the otherwise undistinguished text (no border, same font as everthing else) and right click (who would do this besides the desperate?), the greyed icons now reappear and the hidden devices can be reinstalled or re-enabled ....there are two classes of devices.

Has anyone else ever considered going postal in Redmond?