Land Rover Repair: Key in Discovery wont turn, dead battery, steering wheel

Question
I have had my Discovery II (2001) for about 2 weeks and since we got, it I
have had to try rotating the key like 4 times before it would actually turn.  
Today, nothing I did would turn the key.  I tried shoving it into park, turning
the steering wheel, and taking it out, putting it back in.  I tried for about 10
minutes just to get the key to turn.  So, it is sitting in a parking lot and I don't
want to have it towed, nor do I want to call a locksmith if I don't have to.  I
read somewhere that it could be a dead battery in the key, but I can still lock/
unlock it using the key.  I don't even know how to change the battery if I
needed to.  Could  a dead battery cause this?

Answer
That sounds like the lock itself has failed, which would warrant a locksmith.

It could also be the transmission switch is not making up the interlock.  If the key doesn't think you have it in P or N it will not let you turn the key and start the engine.  This would also not let you remove the key from the ignition but it sounds like you can get the key out.  

A dead battery in the key would cause the security system to prevent starting as well, but if you can unlock remotely the battery should be fine.