Backup backup backup -- sound problem SOLVED using a backup

[Sian Mountbatten <poenikatu@fastmail.co.uk>]

I was playing a music track while using XBMC when suddenly the sound 
stopped. I tried everything I could to restore sound. None of my 
multimedia programs produced sound. Even speaker-test produced nothing.

I tried rebooting, purge xbmc from the system: nothing.

Well, this morning, I unpacked my latest backup of my directory tree 
into /var/tmp and issued the command
   diff -q -u -r /home/sian /var/tmp/home/sian >/tmp/sian.diff
The command ran for a few seconds. Looking at /tmp/sian.diff showed no 
obvious reason why I no longer had sound.

So, I logged out of KDE4 Plasma Desktop, keyed Ctrl-Alt-F1 and, at the 
VT, logged in as root. Then I issued the commands
   init 3                # that stopped kdm and X
   rm -rf /home/sian     # deleted all my files
   rm -rf /var/tmp/home  # deleted the files I had put into /var/tmp
   tar -xjf /opt/cdrw/bd21319-04-25/Phoenicia.sian.tar.bz2 --directory /
# That tar command extracted all the files from the backup and put them 
# into their proper places (each file was preceded by home/sian because 
# tar removes the initial /
I then did the usual sid upgrade commands:
   apt-get update
   apt-get dist-upgrade
   reboot
After the reboot, I logged in and ran speaker-test:
   speaker-test -tsine -c2
Sound from both speakers!
   played some music using Deadbeef (Audio player)

So there you are: a backup saved my bacon.
--
Sian Mountbatten
ex-Algol 68 specialist