Microsoft account sign in problem

Hi

My email address hasn't been working for a month or two now. Everytime i go to sign in, it accepts my password but a message comes up that someone has been trying to get in my account. It then takes me to a page to send a code to a mobile number, however, the mobile number that is showing up is my old mobile number. I have sent a request form to microsoft but I do not seem to be getting any further. Could someone please help?