Corrupt .NEF file

I went looking an image taken in RAW, a .NEF file but could not find it anywhere, so I ran a file recovery program to look for it in case I deleted it by mistake, sure enough I did! (what a tool) anyway I recovered it but cannot open it now, does anyone know of any software that might be able to repair it? please only post something that you have tried, I don't want to experiment installing all kinds of programs. Thx