My ball python is gone!

My ball python was getting pretty big, though it was not really more than two feet long. One day, I took a couple of books off the top of the terrarium, and when I came back the top had been pried open and the snake was gone. I figured that it was under some furniture or behind something, and that after a few days it would show up. Several weeks later, I have never seen it again. I guess it must have taken off through an open door. Since this property has lots of common area that is landscaped, a snake would not have much trouble escaping. Finding mice on the other hand, might not be as easy. Then again supposedly there are mice and rats in most urban areas.