Ok. I remember the “lift the door handle” from an older vehicle my friend had. That’s not the problem. I’m not sure the correct word but it’s the physical part of the lock that sticks up on the inside of the door does not move at all.
Your lock mechanism is probably corroded--if the key in the door lock feels as though it is struggling against something, then you probably need to take the door panel off and spray the joints in the mechanism with white lithium grease, and work them a few dozen times or more until they free up. I had to do mine back in 2009, and since it has stiffened up again, I will need to do it a second time now.