Are you receiving an error message indicating that your e-mail address and/or password is incorrect?
It could be that you were using the app without having registered an account.
Please open the app and answer all of the initial questions once again. Continue without registering and then switch to the Profile tab 
. Select "Save Your Profile".
If you already purchased a PRO account before saving your profile, you can restore your profile as described here.
Certain that you already have an account?
If you believe you already have an account, please ensure that you’ve entered your e-mail address and password correctly and that there are no blank spaces or typos. If you are still unable to log in, please request a new password.
It could also be that your YAZIO account is registered under a different e-mail address or you incorrectly entered your e-mail address during registration. If you are unsure, please submit a request in our Help Center in which you provide your date of birth and your height. We will look into the problem further.
Your e-mail address already exists or is incorrect?
This error message appears when you attempt to register with an e-mail address that is already associated with another account. Please use the button "Log in" in order to log in with your existing account.