Problems signing in
If you're having trouble signing in to the Gmail app for iPhone and iPad, choose your issue below:I forgot my password or username
Click the Can’t access your account? link on the sign-in page.
Here are a few troubleshooting steps to try:
Gmail passwords are case-sensitive, so make sure your mobile device isn't locked on uppercase or lowercase letters.
Try signing in to Gmail on a computer.
Check that your device has an active data connection and can connect to the Internet.
See “Troubleshooting the Gmail iOS app” if you still experience issues with the app.