Before you contact our support staff about your missing account, please make sure that you are trying to connect to the right server. Some updates to your device or the game itself may revert the server you connect on to default, causing you to create a new account on login.
We also need to point out that after a certain time of inactivity, accounts may be deleted automatically or get ruined and removed from the map. For more information on this, we have created this guide. Please also make sure that this is not the case in your specific situation.
Should neither of the above options apply in your case, feel free to submit a ticket to our support team so we can investigate further.