Apparently, the sound needs to be reconfigured on your computer to deal
with the new Linux kernel upgrade.
I'll see if I can get this working this weekend.
https://askubuntu.com/questions/1373232/how-to-force-pulseaudio-to-default-to-the-correct-sound-card-device-port
https://www.reddit.com/r/linuxquestions/comments/1kusymb/only_new_users_have_sound_in_kde/
https://www.reddit.com/r/kde/comments/1kusnru/new_users_have_sound_but_i_do_not/