Sounds like it may have "fused". Hey - it a Fusion, isn't it?
It is a door latch problem, bad news is you will most likely have to take the inside door panel off with the door closed, then - pry on the mechanism to get the latch to release unbolt the latch and replace it
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them