Take it out and try to read from the card using an adaptor in a laptop.
Try to fomat it after removing the files ... if you can.
Never run apps or use screensavers from files on the SD card.
In recent years, memory cards have gained more storage capacity; 4GB and above. The file format FAT32 is now commonly used in memory cards between 4GB and 32GB. If a digital device supports only the FAT16 file system you cannot use a memory card bigger than 2GB (i.e. SDHC/microSDHC or SDXC/microSDXC memory cards).