It sounds like the lock rod or inside door handle control rod has fallen off or broken. Here are diagrams to help you see what's going on you will need to remove the door panel. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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.