Hopefully you have good account recovery information stored with your email provider. If you do not, like listing an old cell phone number, or a deleted alternate email account, then you are really out of luck in recovering your email account. All of your contacts still sending you emails that you can’t access!
Hopefully your security settings are current. It's not uncommon for folks to have no security information stored with their email provider. Google has become better at periodic email reminders for us to review our security settings. Maybe we had entered correct information in the past. However, for a variety of different reasons, our phone number or email address changed since then so those items in our account’s security settings are no longer current. Or, perhaps we didn't write down those challenge security questions and answers. What do you do now?
There is not really anything you can do to retrieve your email account unfortunately. The internet based email providers rely on you to keep your security settings up to date. There is no customer service to call and try a recovery process. Can you seee the importance of securing your email account, just like keeping track of your home and car keys?
Without access to your email account, you may also start losing access to other website when you can not remember your password to those sites. Password resets involving using your email address will become impossible. However, if the website allows you to change your email address, then now is a great time to do so. Not all sites allow you to do so.
If you are using a local internet provider that also provides you with email service, you have a much better chance of recovering your account because you can go their office in person, show them your identification and have them reset your password to your account. There is one disadvantage of using a local internet provider's email services. Should you ever move or change from a local internet provider, the email address you may have been using for a long time will no longer be available to use.