Thanks for your help @walkerland. I'm using Recuva which was also recommended.

No luck so far but I'm getting used to the idea that I have to start again and some of the photos will be gone for good.

I'm not sure how I will back them up in the future. I have so many photos all over the place.

It's a mammoth task to sort them and I can only tolerate doing a little at a time. 😊