No sound on Ubuntu 15.10
Solution 1:
I found the solution (!), create a new file /etc/modprobe.d/intel.conf
add the following options:
options snd-hda-intel single_cmd=1
options snd-hda-intel probe_mask=1
reboot....
Solution 2:
The solution works for Ubuntu 14.10 also! I have HP ProBook 470 G3, too.
Being new to linux, it took me some time to use the hint. This is the full set of commands; the first one creates, the second one edits the file.
sudo touch /etc/modprobe.d/intel.conf
sudo nano /etc/modprobe.d/intel.conf
Type the two options below in the editor, press ctrl+x to exit, type y to confirm and enter to confirm filename.
options snd-hda-intel single_cmd=1
options snd-hda-intel probe_mask=1
Then reboot.