My 1999 Dodge Neon has 85,000 miles

We had the same problem.
Just below the door latch (look at the door jam part next to seat) there's a pin switch sticking out. You need to pop it out with like a small screw driver or something and then it should extend it out and when you close the door again voila it should work.
Its a self adjusting switch and what happened is you probably had your door slammed too hard or something.
Good luck