Well, that seems weird to me you have cleared the cache and the data you have factory reset and now you can't get yourself logged in over your gmail account.
Firstly make sure that you can access your gmail account try signing in over gmail account using PC/Laptop, this would ensure that you remember the access. Also make sure that you have 2-step verification disable as It has happened with me too.... I can't get myself logged over to the gmail account because of the 2-step verification. So, i'll say do check it one you may have accidentally...
Secondly check if your Wi-Fi and data connection is working or not.
Third, again try signing over to the account !!
And the last thing praise me if that helps otherwise wait for the other admins,mod or members to respond !