Hacker on my ahoo account?

someone had hacked into my yahoo account. the email account, that i recieve my college applications, and send all my teachers information.... now, i don't knwo what this person deleted, that was pertienent, including my info that colleges send to me... he sent a website of viagra pills to all my teachers and friends... and everybody has been telling me (wtf). is there any one i can contact so they can fix this... i changed my pword, bu i dont know how long that will hold either... please someone hlp