impossible de me connecter à l'appli

je met mon identifiant et mon mot de passe dans l'appli app store iphone mais il y a ecrit : "login failed : incorrect username or password"

que faire ?

Hello! It may be possible that you're using a wrong username/password combination. Please try the following steps:

1. Please try again using your email address/password combination instead.

2. In case this doesn't help; please check whether you're able to login using same details from the browser.

3. In case you're not able to login via the browser as well; then please reset your password using this guide and try again.

In case these steps doesn't help; let us know.

Thank you!