Sometimes when I start kde neon the audio is not heard, in those cases the word dummy appears in the audio window and there is no microphone and no line-out to raise the volume, when it happens restart and the audio returns, not i know if it's a bug but it's annoying! in the time that you fix the problem (in case it was a bug) is there a command to get the audio back without restarting?

It's been happening a lot to me too lately. I just run from a Terminal:

pulseaudio -k

and it comes back.

Edit: Or run:

systemctl --user restart pulseaudio