How to Recover a Master Document
http://word.mvps.org/FAQs/General/RecoverMasterDocs.htm

McGhie, John
Word MVP Site, The
2005

Abstract:

Notice how this article starts off with the cheerful assumption that you want to 'recover' a Master Document? I bet you were hoping that we would tell you how to 'fix' one! We can't. If you are having a problem with a master document, the problem is the master document. Any attempt you make to repair one will inevitably make your problem worse.