I installed Kubuntu 18.04.3 LTS at the weekend and it all went very smoothly except I had no sound. Zotac Zbox connected to TV using HDMI, previously running Ubuntu 18.04.3 LTS and sound working perfectly, although I vaguely remember having a similar issue when I first installed Ubuntu and it may have been something to do with the NVidia drivers. Tuesday I messed around with the sound settings, moving the High Definition Audio Controller Digital Stereo (HDMI) to the top of the default audio playback device preference list, and it fixed the problem for two days. Tonight I switched on and again no sound. I tried the same thing but this time it didn't work. I followed this guide: https://zillowtech.com/ubuntu-no-sound.html but the alsaloop command never completes. Reinstalling alsa and pulseaudio made no difference. If anyone has any other suggestions would be much appreciated.