micro sd 8GB 4s can't be read anywhere

Memory Cards Mobile memory, professional cards and all other st
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There are no hidden or system files on a memory card, micro or otherwise. It is simply a blank flash memory storage space. You should be able to recover it by formatting it, but if a computer is not ‘seeing’ it, you may have to buy a new card. Luckily, flash memory cards are very inexpensive.