First thing I would do is using your key see if you can lock/unlock the glove compartment. That way you can be certain your fob blade/key is matched to the car. There is also the passenger airbag switch on the side of the dash that is turned by the key. Not knowing the complete history of the car I would start there first.
There is a product I bought from a locksmith "HOUDINI" which I would spray into the door lock and give it plenty of time to penetrate. The old standby WD-40 would work also. Perhaps that would free up the lock.