This came out of no where, everything has been great until an hour ago. I've had the phone since September with no problems and now I get this message saying "Damaged External SD card. Are you sure you want to format the External SD card? All data on your card will be lost."

I didn't do anything. All my music is on that sd card and the last thing i want to do is restore it. i have turned off my phone and taken out the card, but it remains the same.

Has this happened to anyone on here? What to do?