Using Classic Outlook on Windows for personal email, calendar, and contact management
Dear Ahmed Ali Akar,
Thanks for choosing Microsoft community! It is my honor to help you again!
I have read your question carefully and done some research, please kindly refer to the steps as below:
At first, if you are using outlook desktop client, please try to login OWA(outlook web app) to check the result.
You can also use the search function to look for these missing emails: How to search in Outlook (microsoft.com)
In addition, please also try to start outlook in safe mode, the reason for this is to troubleshoot if the add-in is causing this error: Open Outlook in safe mode (microsoft.com)
Then please try to repair outlook file to check whether there is something different: Repair Outlook Data Files (.pst and .ost) (microsoft.com)
If problem, please refer to this article to try to repair outlook application: Repair an Office application (microsoft.com)
Hope this help you, if there is any deviation in my understanding, please forgive me and provide me with more details. I am more than happy to continue to help you. I wish you a smooth new year and all the best!
Best regards,
Kerry