Follow these steps to help fix missing or disappeared folders in your Outlook account:

1. Check System Status: First, check the Outlook system status to see if it’s currently experiencing any technical issues.
2. Disable Add-Ons: If the Outlook system status is normal, try disabling any add-ons running in Outlook for improved compatibility.
3. Verify Email Accounts: Next, look over each individual email account and verify that nothing has changed with the setup or storage.
4. Restart Outlook: If everything looks good, restart Outlook to refresh the current session and folders.