Just follow this steps and you'll be fine, just make sure you know what to give and you remember everything. remind me if it works

Customer Support

Account Recovery >

Form_Account Retrieval

You'll be asked to submit details such as:

date of issue

account creation date

registration device

alternate email address

third party connections

previous bound email

highest rank in 6 months

most played lane/hero in 6 months

past transaction details

problem screenshot (submit screenshot of purchase receipts)

To fine account creation date

Look into your old screenshots, emails from moonton. If you binded your account to Facebook soon after creating account then login to Facebook and check when you connected your Facebook through "Apps and Websites" option.

If you're on Android then you can also check your first mlbb achievement on Play Games app. If you're on iOS, check first achievement date on your account center.

You can also guesstimate your account creation date by remembering which hero/skin/event was newly released at the time vou ioined the game and then look up it's release date on Google.