I'm using a PC. Problem: When trying to export my developed photo in Library, message box appears which reads, "Unable to export . . .Source files offline or missing." How do correct this to export my photo to my hard drive?
Lightroom doesn't find the photos in the expected location that it thinks the photos are in.
This can happen because you (perhaps accidentally) moved, renamed or deleted the photos or folders that contain them outside of Lightroom.
The solution is to use your operating system to find the new location of the photos. Make a note of where they are. Then in Lightroom, you can reconnect to them via these instructions: Adobe Lightroom - Find moved or missing files and folders
As an alternative, if the files were simply moved (and not renamed or deleted), you could use your operating system to move them back to where Lightroom expects them to be.
Thank you, DJ!!