Sorry to hear that - just to confirm, it won't lock with the bipper key fob thing, the door switches on the driver door arm rest and the passenger door itself nor the key in the door turned to lock?
We have to ask these things I'm afraid from past experience.
I doubt it's anything particularly serious. It could be as simple as the actuator rod coming off it's connection in the door. Or a racoon's nest, or a unicorn jammed in there ... They're well made reliable vehicles and not much that we can't help you with I am sure.