Today I was handed a SanDisk Flashcard by a despondent friend. It has never been very reliable & this time had contrived to loose about 350 pictures. I looked on the Web - Google again being my friend - & quickly found "DiskInternals Flash Recovery" for about twenty quid. It was readily downloaded and pressed into service, recovering not only the 350 pics apparently lost, but also a number previously long deleted. Took about an hour of offline time.
It did exactly what it said on the tin and was easy and intuitive to use. I recommend it should you have need of such a thing.
Regards,
Kim Siddorn