Not really true, what does "overwritten (0)" mean?
After a day of trying I used Recuva's Scan Contents... and searched for {"address":
it said it was inside the 17GB pagefile that the new win10 installation is using, I had set it to that size as 6 graphics cards needs it
Recovered it (just copy and save really), used windows cmd FIND "cfebf89f6fcea755ebba061b25a0db398a592055" K:pagefile.sys
As I could not look for strings that have " in them, maybe with escape char? so I could not look for {"address": again. and bingo, ready to copy and paste back the whole ciphertext back in to Mist Ethereum wallet.
The dot in file name is what separates the name and type, so I recreated those for the file, just in case.