If your Outlook favourite folders have disappeared and you can’t get them back again, there are three ways you can fix it:
1.You can create a new mail profile. This resets everything you’ve customized unfortunately, so it is, in my opinion, a last resort.
2. You can close outlook and then go to Start > Run > OUTLOOK.EXE /resetnavpane
3.You can navigate to the folder that Outlook stores settings in. In Windows XP it defaults to:
C:\Documents and Settings\<username>\Application Data\Microsoft\Outlook
and in Vista and Win 7 it is found at:
In this folder you will find a file called Outlook.xml. You should exit Outlook completely then rename the file. Restart Outlook and you will notice all of your favorites and calendars are gone. Reset them to the way you would like, exit Outlook again and restart. Your favourite folders should reappear.
This should work for all versions of Outlook from 2003 onwards.
This post is an updated version of the blog post found here