Your camera might not recognise a memory card if the card has a bad connection with the memory card slot:
- Remove the memory card.
- Wipe the dust away on the terminal with a dry cloth or a cotton bud. Don't touch the terminal with your hands or any metal objects.
- Reinsert the battery into the camera.
Alternatively, you can try a different memory card, to check if there is a problem with your memory card, rather than the camera.
If the problem persists after following the instructions above, the camera may need a repair.