EDIT: I just reread the dialog here and mixed two different response to get the answer below. Are you using the correct key? If you are there has to be a mechanical failure inside the door if it will not open - Unless you have been in the door, this is not likely.
1. Step on the brake and hold it
2. Grasp the wheel about 1 o'clock with your left hand and try to rotate counterclockwise
3. Turn the key
Never use oils in the ignition or on the key, Use some compressed air to somewhat dry it out. Use graphite instead.
