Monitor stays black. touch screen still works

my monitor went black on one of my seven priuses. When I press the info button nothing happens. because I am very familiar with my audio presets, when the screen is black, I can press the FM button and press the audio button and knowing where the buttons on the screen are by the tell tale signs of finger prints on the screen I can change the radio to the preset stations. So, the touch screen works, but I will no longer be able to use my built in GPS. Any body have this problem?

 

does anyone have any ideas of how to resolve the black screen? must be a back light issue since the touch screen still works.