The volume for “IMG_2359.jpg” cannot be found.

Hi

I would very much appreciate someone telling me, in very simple language, what this means--"The volume for “IMG_2359.jpg” cannot be found."

I have looked at this photo before on my iMac, no issues-the only change to my iMac that has been made recently that I am aware of, is the update, today, to OS 10.13.1

If possible, I would like to know how I can recover the file, if the info is still on my computer-can I use my backup hard drive or...?

Thanks

rlmslo