Hacking Account

Hello, My account was hacked. Now I’ll tell you how it was, I sold the account because I left the Minecraft game. I had the MVP + privilege on a major Hypixel project. I agreed with the buyer, he asked me for a password and login from my account to check the correct if I tell him the information about the account, he went to the account via mojang then just somehow removed the mail and put it on, which means it stole the account. The mail on which the account was mine so I can confirm that the account was mine. I’ll ask you to figure this out and I will help I am very grateful to you, thanks in advance!