No sound, speaker not muted, volume control in alsamixer non-functional

[Patrick Wiseman <pwiseman@gmail.com>]

Hello:

On my testing system (ThinkPad T61p, amd64) sound is suddenly broken.
In alsamixer, the controls for headphone and speaker both appear, and
neither is muted, but the up arrow does nothing.  In
/var/lib/alsa/asound.state, where the current state of the sound card
is stored, there are no entries for either Speaker Volume or Headphone
Volume, so I can't correct the problem by editing that file.  Pointers
would be welcome.  Sound was working until recently, but apt-listbug
did not warn me of any issues when last I updated.

Patrick