Hi, I'm Sandy and I look forward to help you today.
I'm sorry about the issue.
In this case, you need to fill out Gmail recovery form to prove your ownership and provide them an alternate working email address.
You may have already filled it, but, still, I'm providing your steps to fill it out as during the last conversation with other expert, it is not mentioned anywhere.
Click the link:
Choose "I don't know my password".
Enter your email address and click Continue.
Under Enter the last password ***** remember, please choose "I don't know" and then click the options shown there and it will re-direct you to the recovery form and it will ask you to fill out details like account creation date, last time you were able to access to this account and many more.
Please fill out as much required details as you can.
Under Contact information, please enter a valid alternate working email address.
Once you fill out all of the required details, Gmail team will get back to you on your alternate working email address in 12-24 hours.
If you have other queries regarding this, please reply back to me the box given below.
And if you can take a second to rate my service(-OK or more -by clicking stars at the top of the page and choose submit), that would be greatly appreciated.