[Nottingham] Sound problem Ubuntu 16.04

[stripes theotoky]

Recently the computer has started popping up a message about an unknown
audio device and asking what kind of device did you plug in.

Screenshot attached.

I have been clicking cancel for the last couple of weeks as I haven't
plugged in anything and the computer has kept working.

Today sound stopped working apart from the sound you get on start up so I
know the speakers can work.

Tried alsamixer everything seems to be turned on.
Tried pavucontrol and can see the sound is working but nothing from the
speakers.
Reboot doesn't fix it.

About a month ago I started to get problems coming back from suspend
requiring logging in again I fixed it with

sudo glib-compile-schemas /usr/share/glib-2.0/schemas

I have no idea if this is in anyway related to the sound issue but it did
immediately precede it.

Any idea most welcome.

-- 
Stripes Theotoky

-37 .713869
145.050562
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