As being a novice with my Mac Pro computer and Cannon 5D mark 3 camera my issue has arisen while over the last year and half, when down loading into my Photoshop Lightroom 4, my 18,000 photograph were not catalogued correctly, or hardly at all, so now over several months time my photos have apparently been redirected in my libraries and have begun not appearing in their allotted frames next to their number in the library they are in. they also have a small question mark (?) next to the photo space. The frames are blank but indicates that there is a photo there. The majority of photos are blank but about a tenth are seen . i apparently need to retrace where they went but do not know how to get that done . can someone help please?
It would be difficult to tell you where to begin. If you moved photos around to different folders and didn't use Lightroom to move them, that would cause Lightroom to lose track of where they are. You have to remember that your images are not "in" Lightroom. Lightroom simply points to them wherever they are on your computer. All of the location information as well as the changes that you make to your images is stored in the catalog, which is a database. This catalog is central to the operation of Lightroom, and it's essential that you understand how it works and how to make it work for you. For all of those images that have "?" On them, or the folders that have the same, you will have to go through the process of locating them and showing Lightroom where they are located. With 18,000 images, and many of them missing, it might just be easier to start a new catalog and organize things properly from the beginning in that catalog.