When you are not unable to access the gmail account on the phone or computer. do not worry, here are the guide to fix such errors. you may apply it on your devices.
1. When you can't access the gmail account on android phone. you should check the user details. most probably, the account details are outdated. that's why you can't access it on your devices.
2. If you are getting the authentication error on the android phone after updating the password. let's go to the gmail website and the your password. now setup this password on the android device.
3. If you have configured your account on the android phone manually, you should remove the current account from the phone and then reconfigure the account. it will start working fine then.
4. Delete the current account from the phone and then re-add the account.
5. if you
can't receive emails on the gmail account on the android phone. please enable the sync settings on your device. now retry to access the account.
6. If these steps doesn't work for you. you should uninstall the current mail app. and then install a new a gmail app. now configure your account on it again. and then access it.