For no apparent reason the sound card is no longer visible in sound settings. Even dummy device is gone. Unsurprisingly flash produces no sound. The sound card is working as the system sounds are still active although sound test does nothing.
What is the problem and how do I fix it (idally without restating)
I have tried
sudo modprobe snd-hda-intel which has been a faithful fixer of sound problems in the past but this was not the case this time.
I followed instructions on restarting pulseaudio (I must confess I was not really clear what I was doing or why so I was probably just wasting time) this has not helped.