740il E38 Nav knob and controls

I have 200 bmw e38 series chasis. I do believe mark 2 nav system. I had every once in a while the nav rotary knob when you touch it it goes crazy. and now I can't use the nav at all. the knob or the radio controls. Now when I turn the engine on I do get a main menu on the screen I can turn from one option to another and when I try to select by pushing it doesn't respond or do anything and my audio power stays on I can't change rhe mode or the tone or eject, basically the stereo controls do not work. The radio does com on but I can't change anything or turn off. I don't feel any clicking in the nav knob.. Is there any solution to my problem and can you give me any tips or suggestion.