Have you been using the card in that device this whole time? Or was it in another device? Also, do you remove the card from the device and use it in others often?
If any of the above is the case, it is completely possible that the card has gotten damaged in all the moving around. They really aren't meant to go from device to device. To see if it is the port, instead of the card, I would try another card in the device. Also, be sure you restart the device before doing this.