Problem with my 2003 Range Rover :(

I recently bought a used 2003 Range Rover with 30k miles and it has been performing wonderfully but now I've encountered a problem. Today I pulled the car out of my driveway and just steered it toward the side of the road and opened the door and put the car in park and took the key out of the ignition then when to grab something out of my house that I forgot. After returning to the car I closed the door and tried to start the car again, but the car would not let me turn the key to start the engine. I insert the key but I just can't turn it to Position II or III to get the engine started, the battery on the key does not seem to be dead nor does the battery of the car. What could be wrong?