Lower Menu shortcuts disappeared

I use a Samsung Galaxy SL I9003 model phone with latest version of Gingerbread on it. I recently started to experience this problem. The shortcut menus on the lower bar have some how disappeared. Here is a screenshot of the same... Screenshot (click image to enlarge) As of now only the Application shortcut remains.. How do I get the remaining shortcut bak ? Thanks P.S : Reboot does not help.