If I don't delete an email, after a while, it just disappears. How can I find it?

Ouijia board?








Depending on what you have and how everything is set up....it might not be there any more to recover. Or it might be.

Is it webmail (which one?), corporate mail, or personal mail account coming to an email client installed on your computer?

Not enough info to go on. E-mail comes in many shapes and flavors. So it depends on what e-mail service, client and how you have it configured.