These is nothing shown on your digital camera, right?
In my personal experiences, your problem could be resolve in these three ways:
1). Try to unhide these files.
According to your description, your files may be hidden anyway. Try to show them all up again:
Start => Run => Type in "control folders" and press "OK" =>Click "View" and hook "Show hidden files and folders"=> Press "OK".
2). Scan your camera with antivirus tool
Sometimes, the virus also would hide the files and make them invisible to you. So, just try to do antivirus scanning on your computer. (You should take care not to delete some needed files in the process.)
3). Restore your files back by using a data recovery program.
This problem also could be caused by the camera memory card problems. So, if you want to save these files, you'd better try to use a data recovery program to take chances.
In fact, there are many data recovery programs available online that can deeply scan your camera memory card and try to restore your needed files. But, not all of them can work as efficiently as you hope. So, in my opinion, you can firstly take chances with some memory card data recovery freeware online that always works more efficiently than some paid ones, such as such as Recuva, TestDisk and iCare Data Recovery Free, etc.
I hope my words can help you out!
Good luck!