If you do not know the Gmail/Google account log in credentials, or have trouble accessing the Gmail/Google account, then you will need to undertake Account Recovery ("AR") from Google, using Can't sign in to your Google Account. There is no other way to recover the account.
The ease and simplicity of Gmail, available across all your devices. Gmail's inbox helps you stay organized by sorting your mail by type. Plus, you can video chat with a friend, ping a colleague, or give someone a ring - all without leaving your inbox. Google Account Recover your Google Account or Gmail Ask questions and get advice on Google Account features and settings. Visit the Google Account community. Share feedback. Report an issue. Let us know if something isn't working Families
Sign in to Gmail - Computer - Gmail Help - Google Help
Account Google Il tuo Account Google ti permette di accedere rapidamente alle impostazioni e agli strumenti che consentono di proteggere i dati, proteggere la privacy e decidere come sfruttare le tue informazioni per rendere gli strumenti e i servizi Google più utili per te. Google Account
Gmail – Apps on Google Play