1. Make sure you are searching for the correct email address.
2. Check any dated emails you might have sent from the missing account to see if it was archived.
3. Search things like spam and junk folders for the missing email address.
4. Reach out to some of your contacts to see if they sent you something recently.
5. Ensure your email client is showing all of its folders on the server.
6. Log out and reboot your device for further troubleshooting.
7. Check the website's search bar for any typed in errors.