Patrick, thanks for the welcome but I've been here for a while.
Anyway, I believe he said his remotes work fine.
I cannot imagine how a key would work to lock the doors but not unlock them as the same tumblers which the key uses to turn the lock barrel to lock the door are used to turn the lock barrel to unlock it. Nothing mysterious about a simple mechanical system like a door lock.
However, if he is locking the door with the doorlock switch, it's quite possible that the doorlock key wouldn't unlock the door simply because it's the wrong key. That could happen if someone changed the locks on the doors and didn't change the key on the keyring prior to selling the vehicle. Some people never use the key but instead, rely on the remote and thus, don't realize that they're carrying around a worthless piece of metal on their keyring until they try to use it. If the previous owner changed the locks for some reason, it's possible this could be the case.
I would suggest that the poster try to lock the doors using the key, instead of the switch or the remote, and see if it works. If it does, and still won't unlock the doors, I don't have the foggiest idea of what the problem might be but he might wish to visit a priest and get the car exorcized.