I can open the door from the outside and from the "lock" lever, but not the actual interior door handle? What is going on??

Mine did this once. It turned out to be the pot metal broke on one side of the handle hinge. It still pulled, but the handle could not push the latch open. It kind of twisted slightly b/c only one side of the hinge was holding. I could not see the problem until I took the handle off .The rod or clip ends could have come off too.

Had similar issue. The screw holding interior handle was a bit too long (I.e. the wrong one!). Correct length cured the problem.

Good luck,

Keith

Its in the door for sho.