You can reset the password ***** https://accounts.google.com/signin/recovery
If you do not have longer your phone number set on the account to recover it, you can click on "Try another way": you will get a proposal for
1) the last password,
2) phone number (new or old one),
3) security question,
4) Verification code by email
5) another email used in the past.
Remember to use a device and the browser you used in the past to access Gmail so will be easier to reset your password.
Account recovery tips:
Make sure to complete the form from a device you have regularly used in the past.
Make sure to complete the form from previously used physical location/IP address.
Answer as many questions as possible, and make sure that your answers are correct.
If you're unsure about some answer or specific dates, that's okay, give your best guess.
Do not attempt account recovery form multiple times in a row because you will get blocked.