Hello Linux Geeksters. In this short guide I will show you how to make the missing network manager reappear in the Unity top panel, on both Ubuntu 13.04 Raring Ringtail and Ubuntu 12.10 Quantal Quetzal.
The fix for this issue is simple, first stop the network-manager service, like this:
$ sudo /etc/init.d/network-manager stop
Delete the /var/lib/NetworkManager/NetworkManager.state file:
$ sudo rm /var/lib/NetworkManager/NetworkManager.state
Turn back on the network-manager service:
$ sudo /etc/init.d/network-manager start