The Folder Pane displays all folders in Outlook. If the Folder Pane is minimized, you won’t be able to see your folders. There are two ways you can view the Folder Pane.
Expand the Folder Pane by clicking the > on the left side of the screen.
Click View > Folder Pane > Normal.
Tip: Click Minimized to minimize the Folder Pane or Off to remove it from the screen.
Note: You can change how Outlook arranges folders by clicking Folder Pane > Options.