I've tried a number of recovery software and probably need to run my PC through a cleaner, but sadly none of them could save or recover older versions of some of my art files. One of the biggest reasons was due to SAI2 type files is not a common one.
I think my best bet from now on is to back up my files on a cloud type server and always use a common art file type.
I am still very sad, but I should look at this as a humbling experience; don't take your work for granted!