Sony Xperia Z — Photos gone weird....half suddenly missing? 😞

Hi,

I hope someone may be able to help me out. A fair whack on pictured on may phone have suddenly greyed out weirdly like the attached picture.

I move data to my sd card when the phone tells me it's getting full. Probably last did it a few days ago.....the problem is affecting pictures and videos in several albums, some whole albums and some just partially.

Please tell me all is not lost and I can fix it?

Thanks for any help you can offer.