Why is the sound missing in Arch Linux?

Question

linux

The sound disappeared out of the blue, I don’t see any obvious errors, I only installed the firefox update.
Played with the mixer, the result is zero.
output of pacmd list-sink-inputs:
pastebin.com/PdvdNsFh
dmesg:
pastebin.com/00FTkPJ8
lspci -k | grep -i audio -A 3 :
pastebin.com/HqLLcSRX

Answer 1

Installed packages:

pacman -Qs alsa
local/alsa-lib 1.1.2-1
    An alternative implementation of Linux sound support
local/alsa-plugins 1.1.1-1
    Extra alsa plugins
local/pulseaudio-alsa 2-3
    ALSA Configuration for PulseAudio
local/zita-alsa-pcmi 0.2.0-3
    The successor of clalsadrv, provides easy access to ALSA PCM devices.

Answer 2

Gnome recently decided to move to pipewire by adding a dependency in one of the packages. The funny thing is that pulseaudio and pipewire conflict with each other. Therefore, when updating, if you agree, then you will be migrated to pipewire, but not everything is so smooth.
I missed during the installation process that the configs changed, as a result, the sound disappeared.
To fix it, go to /etc/pipewire and see what files are there with the .pacnew extension.
The Pacman package manager creates files with this extension if the original file has been modified by the user. For example, if you tweak the original /etc/sudoers, you can get /etc/sudoers.pacnew with a sudo update. This is done by a specialist so as not to ruin your work :)
So for pipewire, it is enough to replace the pipewire.conf.pacnew files and the like with files without the .pacnew extension.
Then restart services:

systemctl --user restart pipewire
systemctl --user restart pipewire-media-session

How to deal with .pacnew files in the future?
If something breaks or doesn't work properly, look for these files:
find / -name "*.pacnew"
And then "restore" manually.