What is the OS of the desktop in question?
Maybe try right clicking on the open desktop, then to "Active Desktop", and see if "Show Desktop Icons" unchecked. If so, select "Show Desktop Icons" and see if that works. The above steps were done on a Win2k PC.
As for the Taskbar, move your mouse pointer all the way to the bottom of the screen, and wait a second, see if it might be set to auto hide. If so it will popup after a few seconds when the cursor is at the very bottom. Then if it does come up, right click, go to "Properties", and then uncheck "Auto Hide".
Hope these help.