How to reset navigation pane in Outlook

The navigation pane is the leftmost pane in OUTLOOK where you’ll find your folder list and the icons to move between Mail, Calendar, People, and Tasks. Running the /resetnavpane command removes all customizations to the navigation pane.
1. Close OUTLOOK.
2. Choose Start > Run.
3. In the Open box, type OUTLOOK.exe /resetnavpane, and then choose OK.