https://social.technet.microsoft.com/Forums/office/en-US/4cdf8f7a-c674-430d-8602-c27ea9a182de/outlook-2010-favorites-disappear?forum=outlook
I managed to get them back by right-clicking on the 'Mail' shortcut in the nav pane, and clicking 'Open in New Window' Will see if it happens again, and if the same fix keeps working. Cheers
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To Microsoft - I have experienced this issue for years, and like some others, have many accounts that make outlook ONLY practical to use if i can navigate within favorites, scrolling through 100 folders to check between 2 inboxes is ridiculous. I eventually did find that a full computer restart(not outlook restart) brought the folders back 90% of the time. Which of course requires me to close every single work project and window i am working on my four monitors. Interesting enough after i setup an exchange account this got worse, so i found this thread. Office 2013 around the corner and no fix, what kind of message does that send users about investing in 2013 with same issues, i really had faith in my favorite tech company that any day this was going to be fixed for 2010.. what do i say to my apple friends? Also spent 3.5 hours yesterday on tech support for exchange, 2.5 was on hold.
To users - I have spent today researching options, and found this as the best process to take for a solid start. (creating new profile is not the answer and a waste of time it seems many vouch for including my situation).
(Skip to step 5 to try and quickly bring back favorites now)
1. Disable all addons not in use
2. Clean up contacts/calendars (for less possible sync issues)
3. install sp 1 32/64bit (google easily).
4. Restart your comp, open outlook only, set all your favorites folders accordingly, close outlook and give it a minute to properly close and save configuration, then restart again.(my safegaurd not fact)
5. Click a shortcut such as calendar or contacts, and then click back to mail.
6. Right-click on the 'Mail' shortcut in the nav pane, and clicking 'Open in New Window'
7. Start-> Run; outlook.exe /resetnavpane
8. Press File the Exit Outlook first
find your Outlook.xml file here : C:\Users\(your username)\AppData\Roaming\Microsoft\Outlook
rename "outlook.xml" to "outlook.old"
Restart Outlook
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I have been directed to test KB2687608. It lists in the notes, "After you add many folders to the Favorites list in Outlook 2010, some folders are not displayed in the list. Then, after you restart Outlook, some folders are still not displayed."
http://support.microsoft.com/kb/2687608
I have installed and restarted Outlook 2010 over 30 times now with no issue. I am about to install on a few users' workstations for additional testing. If this solves anyone else's issue, I would like to know. Thanks.
Alex Gibbs