It sounds like the latch is stuck which you will need to remove the door panel to get at which means removing both drivers and passengers seats. Here is a guide that will give you an idea of what you are in for when removing the door panel with diagrams of the repair below:
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.