In fact, you have a very simple situation.

First you need to log in from your normal IP address, this will help you regain access.
Next, enter your recovery phone number or backup email address (email)
Also, if you can not remember the date, use the usual way, write to support https://accounts.google.com/RecoverAccount?hl=ru


When you are able to recover, do not forget to specify a 2 factor authentication, it will help you to protect your account and in the future it is easy to restore access. https://www.google.com/landing/2step/?hl=ru