Try KnifeST - that's recovered files for me in the past. It's easier with twin drives though.
My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).
I develop a free Word (for Windows) add-in that's available for Word 2007 upwards. It's a fix-it toolbox that will allow power Word users to fix document errors. You can find it at: http://www.mikestoolbox.co.uk
I have already tested with Semprin and of course he can not find any error or file to recover. Normal, I did not erase it. I would have preferred it would not have been very serious I will still test with KnifeST, but I have no illusions.
I second Joska -- I have recovered several times my source code like that. :D You can do that even with PRGs, if the diskette is not very fragmented. Also take a look at Diamond Edge, that was my tool of the day back then.