Depends on which service you registered it with. The e-mail address can only be known by you or the people to whom you sent letters, or just said about it. It's all about the same as the name. If you hadn't written that you are Daria, we would not have known it. If you have lost your address and do not know where you started your mail, the easiest way is to register a new one. But most likely you have a Yandex mailbox, otherwise you would not be able to write here.
Please provide examples.