Comment 5 for bug 285965

I had a similar problem. There was a partial workaround to get sound working again here:

  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/288861

where alsamixer -Dhw revealed that the PCM volume was at zero, and turning it up restored
sound operation. I still have the problem that my system hangs during shutdown while it is
shutting down ALSA. Possibly ALSA cannot be shutdown because pulseaudio -k does not
work, and pulseaudio is an ALSA client.

Here is a list of similar bugs:

#288861
#288652
#288093
#288039
#286966
#286430
#285965