I followed this tutorial of how to make a realistic eye.
Everything was fine; I saved the file and then went to sleep, the next day... BOOM, the textures were gone, and when I check on the nodes I can see they are there but not showing in the 3d view nor material preview, the same with the UV images editor, and even when I made the process over again (selecting all, unwrapping, editing, bla bla bla), they were still not showing.
Everything, every image texture has gone, I mean, what happened? I didn't touch it, I just let it the same as I finished.

– J. J.
Sep 20 '17 at 00:21