Lubuntu 14.04: unmute sound from keyboard not work

When i press mute button on keyboard, it works. But when i press it second times, sound not unmute. How to repair it ?

This key on xubuntu 14.04 works good. Hardware is samsung 550p5c.

Solution 1:

I also had the same problem. Author has provided a link in the comments with a forum post where it has been solved, but for completeness, if somebody else runs into this post, here is a solution.

The problem with unmuting is that pressing the button unmutes only the master channel but not Pulsaudio channels. To correct this one has to modify the keybinding for XF86AudioMute button which on Lubuntu is defined in file ~/.config/openbox/lubuntu-rc.xml. Open the file with a text editor and find <keybind key="XF86AudioMute">, and in <command> section put the following command: amixer -D pulse set Master Playback Switch toggle.

This question has been discussed at askubuntu as well, but that one is actually difficult to find if you do not know that Alsa is the problem, which can easily happen to an Ubuntu newbie.

At the end run openbox --reconfigure to set the configuration.