I wanted to upgrade my sd card to a larger card. I removed the card without unmounting (missed that step in the procedure) it, copied it to a desktop HDD, copied those contents to the new card and reinserted the card into the phone. I did power down before I removed the card and inserted the new card. The mp3 players no longer see my music. I put the old card back and it has the same problem. The files are all there, but I guess the pointers to those have gone. Is there a way to recover?