I run into similar problem with my Ford Focus LZW 2002. I got a new battery and then the CD player stop working. The radio was fine, the player did not wanted to load or find any of the CD already on. Before taking the CD off the dash, I took the fuse off (#31 on the driver's side) and put it back. When I place the key on the starter, the CD changer started to recognize the CDs on it and all starter to work fine.
Enrique Rueda, June 2008