SIM card won't be detected iPhone 4S?

All of a sudden my phone won't detect my SIM card it just says 'No SIM' it will detect every other SIM card but this one!

It looks to me that you have a damaged or malfunctioning SIM card. You see, even the slightest scratch or damage on a SIM card, depending on where it is on the Card, can cause the card to malfunction or shut down. My Suggestion, Don't worry about it, because there's NOTHING wrong with your iPhone, and just go and get a new SIM card.

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