If I remember correctly, when we set up email account security, in addition to asking for a phone number, google also asks us to set up a recovery email. If your primary email is hacked or your password is changed unexpectedly, it will send you a notification to the recovery email. please double check that you have them set up, if so check your alternate email inbox.
I don't remember exactly reading somewhere if our email was hacked and we completely lost access. The last way we can do it is to send report to support and information including primary email, recovery email, phone number and most importantly, the date you created the email account.