2001 Mercedes-Benz ML320, No navagation system?

The screen ,buttons are there,but no navagation! The screen tells me navagation not in stalled. Same with the phone.The phone pad is there, no phone! Why would the manufacture do that ? How do I solve the problem?

These are options, probably dealer installed. Cars are often manufactured with the systems in place for options that not everybody orders, then they’re installed at the dealership for those that order them. Apparently the original owner of your vehicle didn’t want them.