You should contact SanDisk. They should replace it. It apparently had happened with SanDisk cards before just read some of the reviews on Amazon. It might have been a bad card, or maybe this phone has a tendency to kill SanDisk cards, which I hope isn't the case but someone else said the same thing happened to them, having the card for a while and then it being in this phone for only one month, and poof, stopped working.
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