car door will not close

Here's the most likely problem. Look at the striker on the door frame. It is round, about about a inch and one half long, and screws into the door post. There should be a plastic covering around the shaft part where the lock inside the door engages the post. Now compare it to the post on the other side of the vehicle. If the plastic covering is gone, the door will not close properly. A quick fix is possible by switching the post from one door to the other. They are usually removed with an allen rench or star wrench. The slot is at the tip of the post.