Reinstalled windows media player 10 now can't detect songs on C250

I reinstalled windows media player 10 after I had to reformat my hard drive. Now media player won’t detect the songs on the mp3 player.  What do I need to do so that it detects the songs without getting rid of any songs on the mp3 player. 

assuming you have already tried both modes, I would say just back up your songs and re-transfer them onto the player using WMP.