1. Rotate the bottom part (doesn't matter if music or camera mode) 
2. Lock the phone (make sure that you have it auto-locked in the first place) 
3. Return the phone to proper position (number keys at front) 
4. Press unlock then enter the code then ok 

You should be able to access the music keys now as well as the number keys. If you used camera mode instead of music mode, the gallery will be flipped to landscape mode when you access it. The same goes with the image viewer.