Missing materiels in revit

I placed materials to my whole home that I’m designing in Revit and today while I was working a lot of my components just turned grey. They no longer have materials that I set them to have, but the materials are still in the materials library. Does anyone know how I can get them back?

Did you change the location on your computer of the images.
I would try inserting in the image again and see if that makes a difference.