Format it with the SD tool you can download, check the real capacity as there are many fakes sold.
If it's genuine and format doesn't solve the problem then throw it away (or return to seller for warranty).
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Note: This quote doesn't automatically apply to everyone, decide for yourself if it might apply to you.
Originally Posted by justruss
What has this place become?
It's essentially a few people graciously answering the same repeating of immature, lazy, demanding questions from the masses.
Nobody searches. Nobody reads the first posts or titles of threads. Nobody even looks at posts a couple above their own.