My account was hijacked and my security questions have been changed by the person and the alternate email addres to retrieve the reset password is the hijackers info

My account *** Email address is removed for privacy *** has been hijacked.  this is an account that I have never used to send email from although it belongs to me.  I don't know how long it's been hijacked but I do know that i have 2 emails that was sent to this address and the only way I knew is because I received  calls from 2 of the individuals who sent email to *** Email address is removed for privacy *** because i didn't respond so I asked them to forward them to me and sure enough email was sent to this account but when i went to sign in i couldn't when i tried to reset my password i could not use the options listed because the one listed to email password reset is not mine i presume it belongs to the person who hijacked the account as well the security question is not one that i set up or know the answer to so I have no way to retrieve the account please help