Welcome to Android Central! What device do you have? How old is the SD? Try removing the SD card and inserting it into your computer using a fullsize SD adapter (very cheap to buy if you don't have one). Can the computer read it? If not, it's either corrupt or failing. Try reformatting the card, either in the computer or in the phone. You could also try running chkdsk on a Windows computer while the SD card is inserted: http://forums.androidcentral.com/am...guide-using-chkdsk-fix-corrupted-sd-card.html