Then there is nothing you can do. Did you create the account on the phone you no longer have? If so, then it is GONE!
We understand that this is too late in this circumstance, but please always create IMPORTANT accounts, such as email, and lesser important accounts, such as social media, on a landline workstation. A landline workstation can be laptop on wifi, or a desktop on wifi for that matter. The important thing, is the account is created from a WIRED, NON-cellular network.
This way, the provider can offer many ways to recover your account. Always attach a recover email, such as a work, or another email that you will not forget the username and password too (because it SO important)!
After you have attahced another email address in case of forgetfulness, now you can attach a mobile device to the account. If you perform your account creation in this manner, if you lose, break, or stop having access to your mobile device (non-payment of services), you can still recover your account!
It's kind of fun to do the impossible! -Walter Elias Disney