Need a bit more information on what is wrong. Are you using Windows explorer to see the pictures? Are you using the software that came with the camera? Which camera are you using?
There could be a couple of explanations:
Perhaps the last 100 have already been downloaded. Most cameras keep track of which pictures have been downloaded and if you're using software to download new images it would not touch the 'old' ones. You'll need to do a manual download (manually choose which pictures to download from the camera).
Perhaps the last 100 pictures have been shot with the camera using the RAW format (and not jpg). All DSLRs and some point-and-shoot can shoot in this format. If so, you'll need a RAW viewer on your computer in order to see the pictures.
Thanks for the response. I am using a Canon EOS Rebel Xti. I am using the Canon software for the download. I have changed out the card and used a different one and the new card works fine. I am concerned that the card is corrupted and I will lose all of the pictures. Unfortunately it is of my youngest daughters high school graduation.
I downloaded the pictures that the computer reads and then deleted them but this did not help either. The computer does not recognize the card corectly as it does not show any program to download the pictures with, in the pop up window, when I connect the camera to the computer.
Check the file info in the camera to see if the photos were taken in RAW or JPG. If they were taken in RAW you need to make sure you have the RAW codec installed. It should be on the CD ROM that came with the camera but you can also download it here (this is all assuming that you're using a Windows computer):