A couple of more things if you haven't tried them already.
If your not finding your folders anywhere in the menu tree, click the View option tab on the menu bar and have a look around. Also try the Office Button and review Account Settings options.
If all else fails, (and all email is still on the server) remove and re-install the IMAP account. Backup Outlook first. Here's a guide for a Gmail account and Outlook 2010 worth a look.
Add Your Gmail Account to Outlook 2010 Using IMAP