You do not mention your openSUSE version, nor your alsa version. That makes a big difference, and it makes it difficult to try help.
What you could do, is download the following alsa-info.sh script with the wget command:
and place it in your /home/username directory.
Then, if this problem is repeatable, then what would be helpful would be to reboot your PC. Then when you have no sound, open a gnome-terminal or konsole and run the script via:
bash alsa-info.sh --no-upload
and then go to /tmp/alsa-info.txt and copy/save that file as “alsa-info-no-sound-after-boot.txt” into some location that you can access later.
Then plug in your speaker, and if still no sound, run the script again, and this time call the file “alsa-info-no-sound-speakers-plugged-in”:
Then do your “trick” to get the sound working, run the script again when sound works, and call the file “alsa-info-sound-working.txt”.
Then raise a bug report, describing the behaviour and attach the 3 files you created. Info for raising bug reports here:
Submitting Bug Reports - openSUSE