Was the tablet on, shutting down or booting when you removed the card? If so, there is your problem. The device has to be completely off when you remove the card if you are doing a reset.
Your best bet at this point would be to try reading the card from a computer and see if you can transfer the data off the card (the music) to the computer and then format the card and see if it will work again in the phone (without putting anything on it yet). If it reads the blank card/registers it, then you are good and you can just plug the tablet into the computer via USB and move the music back over.
However, personally, I wouldn't trust using the same card after such an issue. Were it me, I would get a new card and install that into the...