Postal address consists of several parts - your name (login), then the icon @. Next is the name of the server to which you are attached. For starters know your username. This can be done through your friends that you sent the message. I think that at least one such person you'll find and it will tell you your name. Now, with your username, it will be easy to learn and password. For these purposes, on all mailbox servers there is a password reset function. For example, you are registered in the postal service Mail.Ru. Go to the home page and enter your username. The postal service offers to answer the secret question. If you don't remember the answer, you can contact the support team. Here the system will prompt you to enter information about yourself. Enter as much information as possible - this will allow you to get your password as soon as possible. To the address you will be emailed a new password within three working days.
There are services that ask for a phone number. Putting the number without spaces or dashes, waiting for the moment when your mobile phone will receive an SMS with a code. Enter the received SMS code and new password. That's all.