I installed or uninstalled some packages. I do not even remember what I was doing. As a result, now I can't see most of the system settings in settings window. Any idea how to solve this problem.
When I hover mouse over the window title, it shows 'Unknown Application name' I must have removed something, not sure what :-)
evolution
; runningsudo apt-get purge evolution*
triggers this. To get the System Settings back without much evolution cruft, I ransudo apt-get install unity-control-center --no-install-recommends
afterwards, some evolution-related components get installed and System Settings with all of its icons is back.