How do I get my account back?

Well someone hacked my account on yahoo and it really is starting to annoy me because I had lots of things on there like important emails from the people I baby sit. Yes I baby sit. I need the money. So I made a call to them and they asked why didn't I reply to their emails and I said I got hacked and now I'm afraid that whoever owns my account is gonna send emails to my contacts that will get me fired. How do I get it back? Or how do I cancel it so that it doesn't happen?