Hello Barbara,
I'm Soji and I'll be happy to answer your questions. I am a Microsoft consumer and an independent advisor with no account access.
For clarity, this is a public user-to-user support forum. We are users just like you who help other users. User account cannot be accessed.
Usually, emails disappear when you accidentally delete or archive them in Outlook. It may also be an indicator of your account being compromised and used by someone else without your authorization.
Also, incorrect settings, rules, and filters may also give the impression that emails are disappearing.
Check your deleted items folder: If the emails were deleted, they may still be recoverable from your deleted items folder. Check to see if they are there and if so, restore them to your inbox.
Check other folders: If the emails were moved to a different folder, they may be located in one of your other email folders. Check your other folders to see if the emails are there.
Check your archive: If you have an archive folder set up, the missing emails may have been automatically moved there. Check your archive folder to see if the emails are there.
Check your email rules: If you have email rules set up to automatically move or delete emails, it's possible that the missing emails were affected by one of these rules. Check your rules to see if they could be the cause of the issue.
Helpful Article: https://support.microsoft.com/en-us/office/email-is-missing-from-your-outlook-com-inbox-c70b4a9a-caa5-4e8c-a88a-3372215af25e
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Thank you for the kind understanding.
Best Regards.