How to repair micro sd 16gb card? It shows 31mb

Memory Cards Mobile memory, professional cards and all other st
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i bought a 16gb micro sd card one off ebay and it will let me store files on it but does not support some files my 2gb one supported, and as i try to format the memory card it also wont let me do that, what do u think the problem is.

hope u can help, cheers (the1withnoname)