To login properly using Words with Friends App, please check these steps:
1. After you launch the app, there's an option to load your game using Facebook if you already linked the game to your Facebook account.
2. If you are not connected to Facebook, you can also login using email or Google by choosing the Other options.
3. If you have an existing account, You can tap the ' Log in Now' option and enter the email that you used to create your original account. Press the 'Next' button to enter your password used when you created your account.
Note: Please make sure that you enter a correct email address to avoid creating a new account.