Teej,
Did you get it working? If the button on the door handle goes in very easy and nothing happens then more than likely a rod fell off. The locking rod that works with the your inside lock button (the thing you pull up and down). If you go to the trouble of taking the door panel off inspect it all carefully. Nothing is more frustrating and damaging to a door panel than off, on, off, on....
And nothing is more fun than working on a door latch in a door!! Long skinny arms small hands and fingers are a plus. I have none of these. With the window all the way up, the door opened as wide as possible, sitting on you favorite milk crate is the best position. Using a flashlight or small trouble light, you can sit there and exercise all the various movements. The most common latch problem is the little spring that actually pulls the latch into the closed position when it hits the door striker plate. They pull though the metal one end and the door kinda just latches, but falls open all time.
Lube it up good and look at all the rods. They are adjustable also. sometimes a small adjustment is needed. Shorten or lengthen the rod. Over the years a latch or lock may have been replaced and then not adjusted properly.
Post how you doing, maybe we can help with some other thoughts!
Rob