An SD card experiencing a fatal error could require reformatting in order to be used. Unfortunately, reformatting erases any data stored on the card at the time. Fatal errors are errors that can be caused by corruption of the card's data, making the card useless until it is fixed.
A fatal error in an SD card can indicate damage to the card itself or a corruption of stored data. It is difficult to diagnose the exact problem without consulting a technical expert. Consult with a technical support professional to more precisely locate the source of the error and determine a fix for it.