Key no longer operates door locks on driver's door. If locked from inside driver's door, doors will lock after a slight delay. Remote is lost for this car.

If key is used to open door from passenger's side, alarm sounds. It always did this since we owned the car...which is why we cannot sidestep the repair issue.

Is best solution to purchase a new remote?

Is it possible that the linkage operated by the key is out of place? It feels like the key is not turning all the way. Could it be the key reader? What else and how difficult to repair/cost?

Thanks for help in advance.