My wife just got a Discovery II and I heard something about when you have a loss of battery power, codes need to be reset for the radio and something else? Wife said she couldn't find anything in the owners manual.

 

You are going to have to bring it to the dealer, they will pull the radio and look up it's serial number and get the code. Do not try to guess it. If you do it might lock out and then you have to sit with the car in accessory for an hour and it's a big pain

 

I'll second the motion.

 

I had luck in calling the dealer and having them look up the code associated with my VIN. If the radio hasn't been changed since the vehicle was originally purchased, this should work; if it doesn't work the first time, STOP! I think you get three tries before it locks out and you have to leave the accessory power on for an hour.