If you are not sure which of your e-mails you used, you can try each of them on that page until you find the one that works.
From the Ticket to Ride and Small World 2 apps, go to the Setting Screen then push the "Account Login" button to open the panel about your account. Then press the "Send me my password" link. If there was no e-mail in your account (which often happens if you created your account through Steam or Game Center), you will have the opportunity to enter it to update your account at the same time.
If everything fails, you can contact us and we will search your account. Please understand that we don't have a crystal ball, so you will need to give us some pieces of information to find your account. We also ask you to try all the procedures described above before contacting us.