I have been running Ubuntu 20.04 and upgraded to 20.10 a few days ago. all went smoothly but after a reboot I noticed that the “Settings” Icon that launches gnome-control-center is missing from “Show Applications” and from the “Dock Bar” menu as well. When I searched from “Show Applications” for gnome-control-center or just settings, nothing showed up.
I figured I must have removed it by accident and figured a reinstall of the package would resolve the issue. I have searched and found several postings where this worked.
# gsettings set org.gnome.shell.extensions.dash-to-dock show-mounts true
Notice the three “disk” icons on my Dock bar on the right hand side.
# gsettings set org.gnome.shell.extensions.dash-to-dock show-mounts false
…and now they are gone.