Missing emails

A number of my emails from mid December have gone missing - they weren’t deleted by me.  How can they be retrieved?

Have you tried "Recover Deleted Items"? Messages deleted from Connect folders are moved to the hidden Recovery folder and are kept there for 30 days, or until the folder contains 15,000 messages, whichever comes first. During this time messages can be recovered (see https://connect.xfinity.com/appsuite/apps/faq/index.html#recoverEmail).