Follow the steps below to fix the issue of missing or disappeared emails in my Outlook mail folders after moving or copying them:

1. Check Outlook folders and settings for any filters, Views, or Rules that could be resulting in there being less emails than expected.
2. Manually check the Trash folder for emails that may have been deleted by accident.
3. Check that the emails are not hidden because of a display filter.
4. Ensure that the Outlook folders and subfolders are properly synchronized.
5. Rebuild the Outlook search index to ensure that any emails missing due to a technical issue are no longer missing.
6. Test for any potential PC hardware issues.
7. Make sure Outlook is set up to receive emails in the right way in the server settings.
8. Check that the correct account is selected as the Outlook's data file.
9. Run the Outlook's Inbox Repair Tool.