Could not be found — this usually means that the photo file (or the folder that contains it) has been moved ,renamed or deleted out side of Lightroom. It could also mean the drive that the photo is on is not plugged in or has changed names/changed drive letter.
The instructions to fix this are: Adobe Lightroom - Find moved or missing files and folders
I have not moved or renamed the photos. The photos are on my mobile phone in lightroom mobile, I can adjust them on the phone but they are not updating on the pc. In my lightroom mobile folder on the pc a lot of the thumbnails are grey and the other images say could not find file, the sync is on. I don't have any question marks next to the images. I think if must be a sync problem with cc. Thanks for helping.
It doesn;t really matter that you think you have not moved or renamed the photos. Lightroom thinks the photos are not where they are supposed to be, and until you can figure out why Lightroom thinks this, you will not be able to fix the problem.
So, what you need to look for is exclamation point icons on the photos, not question marks. Are there exclamation point icons on the photos in Lightroom? An example can be seen at the link I gave.
Thanks dj_paige your a lifesaver, I have now worked it out and all good.
Kind regards David