Ubuntu – Language support

sudo apt-get install language-selector-gnome

reference: http://askubuntu.com/questions/331515/language-support-icon-missing-in-system-settings

Install im-swtich was the problem for me. So this fix this problem. sudo apt-get purge im-switch && sudo apt-get install language-selector-gnome then login and logout and the language icon should reappear in the system settings.