Hi
Have you ever had multiple monitors set up on that computer? It sounds like the Taskbar may have been moved to a monitor that is no longer connected.
Right click an empty spot on the Desktop and select Screen Resolution.
If you see the Multiple Displays options there, select the drop down menu and click the Show Desktop only on 1 option. Click Apply/OK.
Let us know the results.
Thank You for using Windows 7
Ronnie Vernon MVP