Ubuntu 20.04.1 LTS - NetworkManager not appearing in Ubuntu

Solution 1:

Network manager in itself is a service, not a gui for its settings, so it really depends on what are you ACTUALLY trying to achieve...

A) I don't really need the icon, I just want to change some settings or connect to a network (assuming network-manager is running)

• Ubuntu system GUIs often have an application called something like "System settings" - I found it in Unity and Cinnamon (so I expect Gnome has one too) - run that application and in there search for "Network" - there you can usually make some basic WiFi settings & connect
• more "hardcore" terminal "GUI" but very capable: nmtui or sudo nmtui
• for simple gui settings nm-connection-editor - only rich settings, no connect (except auto)

B) I need the icon to be there

You may encounter a situation when you're doing this for a basic user therefore going somewhere further than 2 clicks is beyond their PC skills... so you really NEED the icon #thisreallyhappens or you just love it.
The "icon" is usually there through an "applet" which may crashed or something, we will try to revive it through terminal:

1. Try to kill all instances of the applet and re-run it: killall nm-applet; nm-applet &
2. Exit the terminal with CTRL+D (you may have to press it 2x, it will exit the terminal without killing the nm-applet), alternativelly just nohup nm-applet & for the run should work without this
3. The icon is still not there? Or does it disappear after the restart?
   1. Try to fix your special nm-applet.desktop file as described here: https://askubuntu.com/a/529287/277898
   2. It may be a problem of the System tray applet missing in general (or maybe just the network one) - for that you need to open the "Applets" application and fix it there as described here: https://unix.stackexchange.com/a/280807/223991

C) Get the network-manager service working in the first place

1. Make sure it's installed sudo apt install network-manager on gnome and gnome-based GUIs like cinnamon or MATE you will probably also need the *-gnome versions of packagessudo apt install network-manager-gnome (similarly for all plugin packages you're installing for the network-manager (like the ones OP tried to install))
2. Check whether or not the service is running sudo service network-manager status

   1. Not running?

      1. Start it => sudo service network-manager start
      2. Errors? => fix the startup errors first
      3. Check the status again sudo service network-manager status

   2. Already running?

      1. sudo service network-manager stop - wait till it finishes!
      2. sudo service network-manager start - wait till it finishes!
      3. and check the status again sudo service network-manager status
      4. Is it running? (if not, fix errors first), but still no icons? Try to reboot/restart PC, if still no icon is there, but the service IS running, you can continue with B)

And finally, what OP mentioned: sudo apt-get install network-manager-openvpn network-manager-openvpn-gnome network-manager-pptp network-manager-pptp-gnome network-manager-vpnc network-manager-vpnc-gnome network-manager-openconnect network-manager-openconnect-gnome - those are just common PLUGINS for network-manager to allow you to set-up a VPN connection with some security & certificates settings, they're useful for THAT, but they actually have nothing to do with the network-manager itself nor its icon ;)