How to Restore my Outlook Ribbon

Since resetting the Ribbon did not restore it, please try rebuilding Outlook’s Ribbon configuration.

First, open a new email in its own window and confirm the Insert group is still missing.

Then close Outlook completely. Press Windows + R, enter:

%localappdata%\Microsoft\Office

Find olkmailitem.officeUI and rename it to olkmailitem.officeUI.old, then reopen Outlook. This file stores the Ribbon customization for message windows, and Outlook should recreate the default layout automatically. If the problem is also in the main Outlook window, do the same with olkexplorer.officeUI.

Please note this will remove your custom Ribbon/Quick Access Toolbar changes. Microsoft explains Ribbon customization here:

https://support.microsoft.com/en-us/office/foundations-experiences/customize-the-ribbon-in-office?

If it is still missing, press Windows + R and run outlook.exe /safe. If the Insert group returns in Safe Mode, a COM add-in is interfering with the Ribbon and should be disabled one at a time.

As a final step, update Office and perform an Online Repair:

https://support.microsoft.com/en-us/office/lifecycle/repair-an-office-application?