You've used the Photo Callout tool to place images in your drawing, and they now seem to be missing or invisible.
The Photo Callout tool places images in your drawings with a reference to their Web-based location. This setting prevents you from having to store the images and, in the case of e-transmitting the file, also having to transmit all the photos.
Unfortunately, referencing Web-based images can create a set of specific problems. In rare cases, the source image is actually no longer available – or no longer available at the same Web address. More commonly, this issue will result from a peculiarity with how AutoCAD treats images.
If you open the Xref Manager, you should be able to reload the image Xref. You may only need to reload one image. Sometimes you need to click the saved path, as if you are going to change it, but just press Enter. The image, and all other images with it, will reload. You're of course welcome to send the problematic drawing to us so we can experiment with it as well.
For more information on Photo Callouts, see our Photo Callouts documentation.