Comment 2 for bug 1774979

It appears you don't have a pulseaudio daemon running, which would explain the loss of all output and input.

Please look in /var/crash for any relevant crash files. If found then follow the instructions in https://wiki.ubuntu.com/Bugs/Responses#Missing_a_crash_report_or_having_a_.crash_attachment

Otherwise, please check this page to see what crash reports the machine has automatically sent: https://errors.ubuntu.com/user/ID where ID is the contents of the machine's /var/lib/whoopsie/whoopsie-id file.