Oh man, I live in fear of losing a chapter like that! I know all too well how miserable it is to start over on something already done.
I do have an idea for you though:
If you can remember a few consecutive words from the story, exactly, and enough to make it somewhat unique, then you have a chance to recover it. Word stores it's temp files in weird places. So, the easier way I know to find the text, if it still exists, is to first undelete all .tmp and .doc files. Even if you can't undelete any, it might still be there in a file. So, do a text search in windoes search, use the old DOS wildcards *.* and search ALL files for your text string. You just might find it (I've recovered documents this way).
Also, I advise everyone to turn off auto updates on everything, especially windows. I do my updates manually, and just select the security patches and what I know I need (which is usually a fraction of the crap they want to "update".) For other programs? I don't update unless there is a good reason to do so. If it works, don't fix it.