The first thing you should do is check your Deleted Items folder. It’s possible that the emails were moved there either manually or automatically by the hacker. You should also check the Junk folder to see if any of the missing emails were marked as spam.
If you can’t find the emails in either of these folders, the next step is to check the Recoverable Items folder. To do this, open your Deleted Items folder, and there should be an option at the top that says "Recover items deleted from this folder." Click on this, and you may be able to restore the missing emails to your inbox.
Another option is to use the Restore deleted items feature directly from the Outlook website (which you can access by visiting outlook.com in a web browser). Once logged in, you can find the option in the settings, and it lets you restore emails deleted within the last 30 days. If you’ve already done this and still don’t see your emails, it’s possible that they were permanently deleted.
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hth
Marcin