Either one of the operating rods has come off the handle or the lever is broken. Have a look at RAVE. Only one screw, holds the handle to the door, it's a Torx head the same as the latch retainning screws...don't pull it out when you have undone it, there is a small spacer that may fall into the door cavity if you do.
If the door panel is removed, some of the clips may break, they are only pennies each, best to get half a dozen before you start.