Why the registered account does not exist when logging in?

1. Please make sure whether the app that you previously signed up and the one you're logging in are the same;

2. Whether the country you select when signing up is the same as that when logging in;

3. Is the user name entered correctly? For instance, you misremembered the email account or password;

4. Please confirm the registration method at that time. For instance, you logged in with a social account at that time, but enter an email account now;

If the above problem does not exist after the investigation, please feedback.