Hi!
I showed your post to my brother, and he said first of all:
Don't bother with audacity - he recommends 'Goldwav'
But then he said: "Hmmm, actually, it may not have been audacity's fault."
And he finished with (to me): "Leave that for now, and I'll look in to it."!!
Not the most helpful advice, but I thought I'd let you know anyway as no one else has replied!! Hope you get your files back, and maybe my brother can put a posting up later, if he can make up his mind first!