So what happens when you do try to log into the Gmail account? What app are you using? Do you mean log into an email app, set the account up on the phone, or log into the phone at all? Any error messages? Do you have 2 factor authentication on? Why did you reset the phone (in some cases the reason might be connected to the problem)?

In short, can you tell us everything rather than just "it doesn't work"? To solve it we need to be able to work out the cause, and that requires more information.