Suddenly no sound

My sound stopped working just from doing nothing. I was afk for about two hours and when I came back there simply was no sound. Restarted my system several times. When using speaker-test on my headphones I get the following error: Playback open error: -16,Device or resource busy I asked google and tried some guides but couldn't find any solution. My sound is definitely not muted in the alsamixer

Solution 1:

I facing a problem is, when playing video in the half way. Suddenly turn off my volume, but after i check it all is not mute. I try to go into alsamixer and disable the "Auto-mute" function. Now so far is all work fine for me! ^_^

Solution 2:

If you tried all of the other options available, try restarting the desktop manager(thereby the login session, user-settings, etc). In my case, I did alsa force-load, killall pulseaudio, removed pulseaudio config files, etc, selected proper soundcard, etc - didn't fix. I didn't want reboot just to get sound back. So, I knew restarting lightdm(desktop manager in my case) would work as in many other cases. So, below is the command I ran, logged in and volia, the sound is back!

sudo service lightdm restart