If you properly documented your security info when setting up the e-mail to begin with, you should be able to select that you forgot your password. It then will either send info to a mobile device that was registered with this acct or to another e-mail acct that you would normally have access to.
From my experience going through this, I had it registered to send a link to another e-mail account. I did that and was able to follow the link and answer 2 security questions, and then I was able to force change the password.
Without the mobile or alt e-mail you have to wait on say a 45 minute hold until answered. * Had to go this route before too with a yahoo e-mail once.
They then ask you info and you have to answer security questions. Upon successful completion of answering questions they will grant a password change.
Last option I have heard with other account providers is that you have to scan a drivers license and send this info to them to verify its you, and then they may grant a password change. This only works if the name registered to the e-mail is the name on the license. They also look to see the location it is registered to to match that up with drivers license as well.
If thats not an option then you pretty much need to create a whole new e-mail account and get a note book and write down all info such as password as well as security reset info.