There are a few things I can recommend:
1. Please check your card on some other camera to make sure the media is alright.
2. I am not sure if you take the SD card out of the camera and put it into a card reader (stand alone, in your laptop/PC) to read the images. As I understand, you first took out the card and then put it back into the camera to read from the camera once it did not work in the card reader. However, there are issues with doing both. I will outline them below.
- Card Reader: At times, reading a card in a card reader will mess it up and it will remain unusable in the camera even if it displays photographs on camera LCD. Please note, this will happen even if you have only viewed the photographs on your computer and not saved them to your hard drive/media. The card will most definitely not work in camera if you delete photographs from the card or edit them on the card. The only solution to this is to format that card IN the Camera. The manual has instructions for the same.
- In Camera: Other times, you may have connected the camera through the USB cable to a computer with the card in the camera. This problem may crop up IF you used your computer to delete images from the card whilst it was IN the camera. Again, the solution is to format the card. IN the camera, not from the PC.
3. Whether you use the USB
cable or take out the card and put it into a card reader to save your photographs, always repeat ALWAYS format your card in the camera after transferring
your photographs. This ensures card will not malfunction unless the media is corrupt. This also has the added benefit of not having the same photographs a few times over.
4. Try not to leave your images in the card after taking photographs. Try to save them to your PC at the earliest opportunity
. Format after-wards
(I can not repeat this point enough).
5. Use multiple cards of smaller capacity. They are cheaper to buy. Even if you lose one card to a mal-function, you still have photographs on others.
I hope this helps.