Segapunk

Hi Guys, I have a 2012 Lexus ct200h f sport and the dat nav screen in the car is no longer showing any picture. I can connect to the Bluetooth which works fine, the radio works, everything is working as normal however my display screen is blank. I went away for 12 days so the car has been sat on my drive and when I came back, the navigation screen opens up but nothing is displayed. The functions seem to be working just no picture. Any ideas? Thanks in advance