Question about Outlook Express

This concerns the Windows Live Mail client; that is the email program.  Aside from four separate POP mail accounts, I have created, named and set up certain 'Storage Folders' where I drag and drop incoming mails to be saved by category.

Some 'hiccup' happened recently, where messages in certain Storage Folders were 'auto-copied' by WLM and appeared as unread messages alongside the originals in these folders.  Without thinking, I simply deleted the unread copies, only to find a bit later that the 'originals' had become corrupted in the WLM self-copying process and could not be retrieved, moved, or even deleted.

I have the original messages on a system-wide backup drive but can't figure out how to get them back into the WLM folders.  If I go into my computer's menu tree using Windows Explorer and simply copy all the email .eml files from the backup drive to the correspondingly-named WLM files, they become resident in those files, but the emails (with To:, From:, Subject:, etc. info) do not appear in the expected folder on the WLM screen.  Similarly, if I drag and drop an email within WLM into that folder, it does not show up as a .eml file in the menu tree folder.  It's as though WLM has a 'secret' file location somewhere other than where it says it's storing all the mail.  Either that, or the email ID is stored separately from the .eml file... don't know.

Can someone supply a quick tutorial on this topic?  Many thanks!