Lightroom 3: Unable to view images

Hi! I am having an issue viewing the images in my folders in Lightroom 3. The content is obviously there, because I can click on them and export them as they are. Unfortunately, I am just unable to see them at all while in Lightroom. It just shows a blank gray square. Any help would be wonderful. I also tried to upload the newer Lightroom 6 that I purchased but when working with an Adobe agent we were unble to get the catolog to work. He says it may be a corrupted catolog. Any idea how to fix that issue? At this point I am considering removing Lightroom and trying to re-upload it from scratch. Unfortumately, all of the images I have taken for several years will disppear if I do that. I would rather fix the problem.

Thank you so much!