How can I recover my account?

If you did not bind the game then it is not saved. You can try the steps listed here https://www.appgamer.com/last-shelter-survival/strategy-guide/how-to-reset-your-password-for-im30-accounts to contact the game support and give them your game details (name, state etc) and they may be able to help recover it.

I know this is late but for anyone else in the same boat, when in the game click switch accounts then enter the email of the lost account and click 'reset password'. You will then receive an email with a new password, once you have this reload the game enter email and new password. This should work and worked for me, it will load stating the last game play, state location and alliance. (Tip: take a screen shot of this info or Wright it down incase you ever need to email the developers as they do need the state name) your game will now load and you should find it easier to jump between accounts as I have.