How can I reset audio settings to the original / default mode?

I messed up the audio settings and now I can’t use Skype because the computer doesn’t “listen” to the microphone (plugged or not). I can hear, but they can not hear me, as if my microphone is off, but it is not. I used Pulse Audio Volume Control to try to record the computer sound using Audacity, but I only got the problem described. Is there a way to reset the audio settings to the original mode (ubuntu 18.04.4)

If the issue is strictly related to pulseaudio settings, yes resetting it will do the trick.
Simply delete the configuration files and restart pulseaudio :

rm -f ~/.config/pulse/*
sudo killall pulseaudio
# daemon(s) will restart imediately

More information : https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/