Comment 19 for bug 1799007

I think the main hint is in comment #15:

  tessa@viper:~$ pacmd list
  Daemon not responding.

This means pulseaudio has either hung, crashed or been killed. Please follow these instructions to see if you can find any evidence of a crash:

  https://wiki.ubuntu.com/Bugs/Responses#Missing_a_crash_report_or_having_a_.crash_attachment

If not, and if the pulseaudio daemon is still running and not responding to 'pacmd list' then please try forcing a crash report with:

  killall -ABRT pulseaudio