To retrieve your old account, you first need to create a new account. While logged in to your new account, click the Settings button in the lower left corner.
Make sure it is connected to your Google Play services.
You need to have played enough on this new account to set a username.
You'll find your username along with the account# in the Settings menu here:
Send us both your new username and your old username by submitting a request. Remember to include the account number#.
We will then connect your Google Play-ID to your old account. We will send you a confirmation and you can now log back in. If not, you could try to re-login to your Google Play on your device, and re-install the app before trying again. That should solve this issue and you should be able to login to your old account!