Ubuntu 16.04 streaming video has no soud

This is what I have installed: Ubuntu 16.04 dual boot with Windows 8.1, FF 60.8.0esr, My sound for streaming video does not work, tried with Youtube, no sound, but my local files (video & audio files play fine). I had previously problem with missing items in my desktop, had to run this command to get back

sudo apt-get install ubuntu-desktop 

how can I fix this problem? Already tried to remove/install ubuntu-resctricted-extras and pavucontrol.