Sometimes your Ubuntu sound system can stop working. Often this is caused by a media player plugin in your web browser. You might also notice that your computer goes very slowly and that if it is browser-related, then the browser will perform at a snail's pace!
As a Linux user, you will no doubt consider rebooting to be a personal failure! It's also annoying if you have loads of apps open, as I usually do. However, restarting the sound system whilst keeping your system alive is actually pretty straightforward. Here's how...
1. You need to find out what sound-based process(es) are actually running. To do this open a terminal and type:-
lsof | grep pcm
This will return information similar to this:-
mplayer 23915 garf 83u CHR 116,16 11782 /dev/snd/pcmC0D0p
mplayer 27456 garf 83u CHR 116,16 11782 /dev/snd/pcmC0D0p
2. Kill the offending processes, like this:-
kill -9 23915
kill -9 27456
Important! Substitute "my" numbers with the numbers that lsof | grep pcm actually returns for you!
3. Restart ALSA (Advanced linux Sound Architecture) assuming that is the sound system you are using. In Ubuntu you do it like this:-
sudo /etc/init.d/alsa-utils restart
That's it! Your sound system should be up and running again. Moreover, if the problem was browser-related, then your browser should start running at normal speed again too.