Have you tried leaving the card in the camera and then connecting the camera to the laptop via USB? That is usually the best option (rather than taking out the card every time) as over time the charge will get damaged.
If the card is readable by the computer and the camera, but the photos are missing (even on the camera when you put the card back) then they were deleted. How, I can't say. But I would really try connecting the camera to the computer, with the card in the camera, first.