My doors keep locking and will not unlock what can I do to fix it?

You'd be surprised at how often the door lock/unlock switch in the driver's door is used. It's fifteen years old and likely just broke. As the doors lock properly, I suspect that you just need to replace the switch, but it is possible that the problem is in the wiring that runs from the door to the body. Each time you move the door, the wiring harness flexes and wires sometimes break. Address the switch first; that's the easiest to do.