Hi ! This is Benpella . I'm a fellow Outlook.com user and I'm sorry to hear about the issue.
If your Office 365 Groups have suddenly disappeared, here are a few steps you can take to troubleshoot and potentially resolve the issue:
Refresh the page and clear browser cache: Sometimes, the disappearance of Office 365 Groups can be due to a temporary glitch. Refresh the page in your web browser and try clearing your browser cache to ensure you're viewing the latest information.
Check the Deleted Items folder: Office 365 Groups that have been deleted are usually moved to the Deleted Items folder. Go to the Outlook web app and navigate to the Deleted Items folder to see if your groups are there. If they are, you can restore them by right-clicking on the group and selecting "Move" > "Other Folder" > choosing the desired location.
Verify your permissions: Ensure that you have the necessary permissions to view Office 365 Groups. Contact your IT administrator or the person responsible for managing your Office 365 environment to confirm that your account has the appropriate permissions.
Check with your organization's IT support: If you are part of an organization, reach out to your IT support team or helpdesk. They can investigate the issue further and provide specific guidance based on your organization's setup.
Restore from backup: If your Office 365 Groups have been permanently deleted or can't be recovered using the above methods, check if your organization has backups or a retention policy in place. You may be able to restore the groups from a backup or contact your IT department to assist with recovery.
Benpella