Please check the following information to find your account.
1. Go to Apple’s homepage (https://www.apple.com/) > Click the shopping cart (bag-shaped icon) on the top right > Login > Click on Forgot your Apple ID or password? > If you have forgotten your Apple ID, click Find ID
※ Account not linked to Google Play/Apple/Facebook: Unrecoverable in case of loss
No information is collected for guest accounts and they are stored only on the device. If the account is lost due to factory reset or device change, it is not possible to recover it, so please make sure to link your account.