Hi Peter.
You would almost certainly stand a better chance of recovering some of the images if you had access to the original memory card that they were saved on.
I have had great results using Testdisk and Photorec.
http://www.cgsecurity.org/Photorec scans the whole drive for datablocks and will definately recover some, usually most, and if they have not been overwritten by subsequent saves to the file system, potentially all of the images.
I have only used the Linux versions, but they appear to offer free download for other Operating Systems too.
I hope this is of some help to you.
TL;DR Send this link to whoever has the physical media. :http://www.cgsecurity.org/wiki/PhotoRec