someone else is using your account

like many users, ive received this error message when i tried logging in to MY account. i've tried entering my security answer but it says wrong. the alternate email address isnt sending to the right email address. ive also done the validation process by the outlook team have yet to get back to me. please kindly check it for me and get it ASAP! ive been using this account for sch related activities. my university is about to start and i need to get this email account to be recovered as soon as i can so i wont be missing out on any important dates or registration for my sch!this is driving me crazy! HELP PLEASE!