Problem connecting my MacBook Pro to a Vizio Monitor The HDMI port on my MacBook Pro doesn't seem to be functioning normally.

When I plug it into the TV, the screen temporarily turns black as if it is connecting to the TV, However, it only shows part of my computer desk top.  I can see the background and the top row of information.  Nothing else is up there...no mouse, no folders, nothing along the bottom. What is the reason for this? It was just working fine a short time ago.
It is most likely that your TV is showing a secondary screen view, where little other than the background shows by default.

Try Settings>Displays>Arrangement, then check 'Mirror Displays'. This will duplicate what is on your laptop screen onto the computer. Uncheck it, and you now have two displays, with the relationship between them shown in the graphic within the 'Arrangement' tab.

The reason you see only the background, and 'top row' is that is how OSX displays the secondary display. The Dock is not visible, and there are no folders there...because you have not put any there. 

Try this: attach your TV, then drag a window onto the TV. You need to drag to the left or right of your laptop screen, but you should see the window show on the TV.