When playing back images on a camera, if the "Cannot playback image" message appears, the main causes are as follows.
1. You are trying to play back images captured with a non-Canon camera.
2. Images in the memory card have been imported to a computer and rotated or edited and then written back to a memory card.
Import the images to a computer and check if they can be displayed. For information on how to import images to a computer, please see the EOS Utility Instruction Book bundled with the camera.
3. The memory card is malfunctioning.
If you have multiple memory cards, initialize another memory card and take some test shots. If images can be played back normally, the card that shows the error message may be malfunctioning.
In this case, initializing the memory card may solve the issue.
When the card is formatted, all images and data in the card will be erased. Even protected images will be erased, so make sure there is nothing you need to keep. If necessary, transfer the images to a computer, etc., before formatting the card.
For more information on how to format the card, refer to the instruction manuals that came with your camera.