I am not sure what changes I made in an attempt to find out why my microphone wasn't working well, but the result of my undocumented changes is that now I have no audio at all on my Dell Vostro 3450 Laptop.

The Sound settings --> Hardware tab, which used to show an audio device, is now empty.

I tried to remove and then re-install packages that had to do with audio (pulse audio, alsa), but to no avail.

How can I get my audio back?