Comcast is a cable provider whose services include cable Internet. If you use Comcast and your email messages disappear, you can contact Comcast directly to see about restoring them. Keep in mind that several factors--including the type of messages, your operating system, and why they disappeared--will influence how often Comcast can restore the messages.
Click on the Comcast Customer Support link (see references).
Choose "Internet." Click on "Contact Us" and use one of the directions on that page to contact a customer service representative. You can do so by phone, email or live chat.
Provide your name and account number to the representative and explain to them what happened with your emails. The representative will usually be able to go into their servers and restore the missing emails. Depending on the amount of time that has passed and the reasons your messages are missing, however, some might not be restorable.