$ sudo apt-get update
$ sudo apt-get install indicator-applet-complete 

indicator-applet-complete is installed in your system.

Make ensure the indicator-applet-complete package were installed using the commands given below,

$ sudo dpkg-query -l | grep indicator-applet-complete *

You will get with indicator-applet-complete package name, version, architecture and description in a table

indicator-applet-complete package basic information: