

In Outlook, this is found at Tools > Accounts > Edit the email account > More Settings > Advanced > check box for Leave a copy of messages on the server. To prevent this from happening, be sure to set your POP3 account to leave copies of messages on your server.

Check the Outlook or other mail client on that computer. If you made a POP3 connection via Outlook or another mail client, then the emails may have been moved to the computer which made the POP3 connection.

Check your other folders, especially Spam and Trash. It is possible someone logged in and deleted or moved the emails. There can be several reasons for why your emails seem to have suddenly disappeared. Search Bluehost Web Hosting Help Email Troubleshooting - Emails Suddenly Disappearing
