Audition removes file from drive

The only way that Audition will wreck a file is if you do it deliberately (or 'accidentally' deliberately, I suppose). You would have to open the file (not just have it in the browser) and deliberately remove a large chunk of it, and then save the result. You'd be prompted to save it before you closed it, and that act of saving it after editing it would be the only way of wrecking it.

Those of us that do this for a living have a cardinal rule - never edit the original - always edit a copy. That way you've always got something to go back to. For me this is relatively easy with production work, as I don't record in Audition; I always have original files on completely separate media that are copied to the machine for editing. If you are recording using Audition, you have to be a little more careful though about making backups.

The chances are that all Audition has done is to delete it from the files list, as you said. Your problem simply is that you can't see it, for some reason. Audition doesn't delete files permanently when you hit that trash bin button - in fact it makes a considerable point of not doing so. If you hover the mouse over it, it says 'close selected files' and doesn't mention deleting them at all. Also, if it had, it would have put it in the computer trash, and according to you it hasn't, so there's a very good chance it's still somewhere on your computer, I'd say. You may have to do a proper search for it though.

The location of the .pkf file might give you a good starting point as to where to look carefully though. That file is a file created by Audition to store the visual information about your file so that it can re-open it quicker - especially useful with a large file, and is generally co-located with the appropriate wav file.