Check if the images can be seen in camera
. Reset the camera
. View the first image
. Decrease the zoom till around 80 images are displayed, and then scroll
If images are displayed, then the camera is able to read them. If some are still missing, then they were either not written or got corrupted.
In case the images are missing, then you can use a data recovery program to see if any image can be recovered.
Your problem may either be the card or the camera. If only some in the middle are missing then most probably you switched the camera off before the image could be successfully written. I find it best to review the images on the display immediately. If I am shooting a long sequence, I review them at the end of the sequence. As the saying goes, better feel foolish checking and rechecking, rather than lamenting lost images at a later date.