I just cleaned up junk files on my Ubuntu 12.04. After that, I restarted my Ubuntu. But then, I lose the network indicator in the Unity panel. I don't know how to restore the network icon as before.
It can be reinstalled!
Hit Alt+Ctrl+T to open terminal and run following commands one by one:
Restart your system for the change to take effect.
I found this solved my problem on Ubuntu 12.04