Where did all my Outlook mail go?

I recently attempted to switch OS X Mail from using POP to using IMAP to access my Microsoft Outlook (msn.com) e-mail account. In doing so **all** mail in my Outlook account older than a week *disappeared*. Where did this mail go and how do I recover it? --- FWIW, I've switched back to POP (IMAP appears not really to work), but the missing messages are still gone (and they're missing from outlook.com too). And FWIW, here's what my "Activity" looks like after creating the Outlook.com IMAP account (while nothing beyond a handful of messages has appeared in my OSX client): Meanwhile, the number of unread messages I see on iOS for the same account (synced using an "Outlook.com" account) is ***diminishing***! Weirdly, when (and only when) my network connection is interrupted (e.g. if my system sleeps) the number of messages in my MSN inbox jumps a bit.