Shortcuts dissapeared.

When gnome is started up normally you get shortcut icons for your root
directory, the trash bin and others.
But I have lost those shortcut icons. Also clicking on the right hand mouse
button while on the mouse-pointer is on an open part of the screen does not
give a menu to open a new window, or terminal..
How can I restore the icons on the screen and make my linux system react on
the right hand click again ? Is there a configuration file or log I can
inspect to see how this could have happened ??

Thanks for any help,
Marc