in Linux, if audio doesn't work, you can try
pulseaudio -k # kill it
then wait few seconds for it to die. You can check by
pgrep -l pulseaudio
then, start pulseaudio again.
pulseaudio --start # start it again
To start the sound level control panel, do:
setsid pavucontrol # start sound level control panel
now, if your desktop dock volume shows gray, you might need to restart it.
# restart xfce dock pkill xfce4-panel setsid xfce4-panel
The Linux audio problem is caused by the kernel having problem with several popular Logitech webcam. In my case, its Logitech HD Webcam C310 amazon
In your syslog,
tail -f /var/log/syslog, you get flooded by this message:
kernel: [ 1438.563209] 3:3:4: cannot set freq 48000 to ep 0x86 kernel: [ 1438.563976] 3:3:4: cannot set freq 48000 to ep 0x86 kernel: [ 1438.565348] 3:3:4: cannot set freq 48000 to ep 0x86
The solution is just to unplug that webcam.
You can see bug report here. https://bugzilla.kernel.org/show_bug.cgi?id=44281