My email was hacked

What does a person do if there email was hacked into...I went log into my account and it kept saying someone else was using it so I had to answer a bunch of stuff to verify it was my account. I then had to re-answer them cause I did not provide enough information. So once that was done I had to reset my password, and when I had signed in someone had sent stuff to people from my contacts. I dont know what it is it is a file I think. It comes up as a shape of a picture with a paperclip on it and says 2.4 mb not sure I was scared so I immediately looked to contact hotmail or outlook whichever as my account is hotmail but you guys changed to outlook. Anyways what do I do cause I never sent those things and I dont know what they are.