Try cleaning the gold pins with windex or 90% rubbing Alcohol. Dry it with a cotton or microfiber rag, then let it sit for a bit to make sure it's dried. When it is dry try reading it again. If you are still getting nothing then it's most likely a dead card, if you do get something then it meant that the pins had some corrosion on them. That usually only happens if the card had overheated. In that case be sure to backup which files that you can from the card, then get a new card. You do not want to put components that have a heat problem back into your phone as it can cause damage.