Can't reset apple id security questions

I really need to reset security questions on my apple id cause someone changed it,but when i try to do it here : https://iforgot.apple.com/password/verify/appleid?prs_account_nm=makar.makar.mak ar%40mail.ru&autoSubmitAccount=false&sst…

it says : "

Cannot Reset Security Questions

We don’t have sufficient information to reset your security questions. "

What can i do?Please,help me!