Iphotos and videos have gone grey.

They are all there, can even see length of video although its just grey/white. The photo opens but you can't see it and when you open a video it says, Cannot Play Video. Photos cannot play this video because it uses an unsupported formal. Please help because they used to work fine. Tried option command to repair and no good. Computer had a virus and its fixed now and it migrated the photos over to Photos. They are all there but just grey squares.