98 Lincoln Navigator wont go into drive

I have a 98 lincoln navigator with around 130,000 miles on it. After a recent vacation the brake line busted leaking brake fluid everywhere. That was repaired by a mobile mechanic service. Then the next day my fiance drove it to work and when he went to come home the truck wouldn't go into drive. It starts fine the battery is good but Someone recently mentioned something about wiring problems or something to him. We are both lost and I was just wondering what the cost to repair something like this might be or if that even might be the problem. Any advice would help. Thank you!

-Amanda