I'm new to linux, I don't know what went wrong, I typed apt-get upgrade in terminal, and after that the sound is disabled, and I can't control screen brightness anymore.And it's only on root account. The sound is enabled on other accounts. I'm running Kali Linux 64 bit version 2016.2.
Sound and brightness control disabled after apt-get upgrade
kali linux
from kali linux official issue page :Those issues are due to GNOME being in transition between GNOME 3.20 and GNOME 3.21 in Debian Testing currently. We have to wait until updated mutter/gnome-shell enter Debian Testing (and thus Kali Rolling).but you can use xbacklight to change brightness from the command line, to install it open your terminal and type :sudo apt-get install xbacklightthen type xbacklight -set 30 to change your brightness to 30% for example. 