i have a 2006 audi a8l q

ok here is the situation... i was going into the city with my wife to enjoy a nice dinner,.. and the radio was working fine and the screen popped up with no problem... once we finished the dinner and i went back to the car i turned it on and the screen didnt pop up or the buttons for the fm/am, nav, car, etc.. did not light up..

can any one help...

thanks