Good suggestion, @loganlamar & @creative-click-photography! No need to call in the big guns if all you need is a USB cable… 🙂
@hannahm, if that suggestion does work, then I would suggest that you rescue all the photos and make sure they’re not corrupted, then format the SD card in your camera.
Here’s a tip for the future to prevent this from happening again… Whenever you buy a new SD card always format it in your camera before using it for the first time. Cameras (and Windows computers) can be a little finicky about how SD cards are formatted, so you definitely want to start out fresh with a clean format when using it for the first time.
If you still have trouble with Windows recognizing it after that, then consider sending the SD card back for a refund. There are plenty of cheap Chinese counterfeits of SD cards available on eBay and Amazon, and it’s possible that you got a lemon. I always recommend that everyone stick to B&H or Adorama for stuff like that. The price difference isn’t enough to be worth the stress and trouble of lost photos! Of course, there can always be “lemons” even among genuine name-brand electronics too, but Adorama and B&H will be there to help if that’s the case.