Phone number changed and forgotten password

hi, ok so i recently got a new phone number and i cant remember my password to my gmail account. i have tried filling out the questions for the recovery proses an email to send a reset code to did not work and it keeps just telling me it is unable to verify the account and to try a new one. i have a number of important documents on this email and i need access to it, i am not quite sure what to do and i would really appreciate some help.
thank you