It appears part of the problem here is timidity (bug 1793640). Please uninstall timidity and timidity-related packages and reboot.
If that doesn't fix the problem then please try live booting Ubuntu 19.04 from USB to see if audio works there:
GNOME: http://cdimages.ubuntu.com/daily-live/current/ XFCE: http://cdimages.ubuntu.com/xubuntu/daily-live/current/
It appears part of the problem here is timidity (bug 1793640). Please uninstall timidity and timidity-related packages and reboot.
If that doesn't fix the problem then please try live booting Ubuntu 19.04 from USB to see if audio works there:
GNOME: http:// cdimages. ubuntu. com/daily- live/current/ cdimages. ubuntu. com/xubuntu/ daily-live/ current/
XFCE: http://