Google couldn't verify this account belongs to you

Ajmer my Gmail was logged in in only one device, and for some weird reasons my device got reseted. From them I am not able to get access to my email account I had tried many times recovering my account but it asks for a backup code which I have lost while resetting I have a recovery mobile number added to my email but Google doesn't show any options, I click on try another way it directly says Google cannot verify this account belongs to you.