It sounds like the passenger side door module has gone out but to be sure lets make sure it is getting a signal. You will need to remove the door panel which means the passengers side seat will need to be removed before you begin. Here is a guide to help you test for signal out of the module to unlock the door latch:
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.