Hello Teresa Stahl, thanks for posting this in the community.
Sometimes folders appear missing because of view settings. In Outlook Desktop, go to the View tab, then Folder Pane, and make sure it’s set to Normal. In Outlook Web (OWA), click the menu icon, scroll down, and ensure Folders are expanded.
You can also search for the missing folders by using the Search bar to locate an email you know was in the missing folder. If the email appears, check its current folder location to confirm whether the folder was moved or deleted.
If the folders were accidentally deleted, check the Deleted Items folder. If not found there, use the Recover Deleted Items option available in Outlook Desktop or OWA under Deleted Items to restore the folder or emails.
If you use a local PST file, go to File, then Open & Export, and select Open Outlook Data File to check if the folders are in another PST. If OST corruption is suspected, close Outlook, delete the OST file, and restart Outlook so it can re-download the data.
You can also log in to Outlook Web at https://outlook.office.com. If folders appear there, the issue is local to the Outlook client. If they are missing online too, the folders were deleted or moved on the server side.
Kind regards,
John Oli