desktop and start bar not visible in vista home

Press CTRL+ALT+DEL and start Taskmanager. In Taskmanager check, whether explorer.exe is listed in the process list. If not, choose "File", "New Task" in Taskmanagers menu and type in explorer.exe. Click OK and see, what happens. If the desktop is back, check the event list for any errors.

absolutely amazing--worked immediately!! many many thanks, chrissie

You have to try restarting the computer to figure out, whether it works without Taskmanager / explorer thing.