Audio vanished with jessie

[Hendrik Boom <hendrik@topoi.pooq.com>]

It's an ASUS 10000HE running  jessie.

Today sound wouldn't work, though it worked a few weeks ago.

I won't say nothing has changed; I have been doing regular upgrades using 
aptitude.

I don't even know how to begin diagnosing the problem.  No sound, neither 
in audacity nor in VLC.

Neither paplay nor aplay give me any sound.

The audio device is *Enabled* in the BIOS.

What tests should I be performing to narrow down the problem.  Or is this 
already a well-known bug in jessie?

-- hendrik