|When you format the card on a phone it creates separate folders for pics, videos and mp3s and gives those folders names. If those folder names are not the same as what the second phone would use then it's possible that second phone will not be able to access those folders and might see the card as blank.|
It also seems not uncommon for those cards to lose their data when moved around to other hardware.
If you use a PC card reader you should be able to see whatever is still on the card.
If you format the card in the new phone then it'll be usable but empty. If you want to make sure you save what's on the card then first use the card reader to transfer the files on the card to your PC.
It may be difficult to get the files back on the card in the new phone as phone cards are often seen as read-only by a PC. In that case you may need to email them to your new phone.