how to trace yahoo id - URGENT

[forever]

guys , thers this guy who is troubling me a lot , all i know about him is his yahoo id , is there any way i can know more about him , u know his profile or password , i dont have the slightest of clues , hey if it is illegeal to post then please pm me , it is really urgent , thanks guys ...

[Thor]

File a complaint against him @ yahoo ! Hope they divulge !
And to get rid of him block his mail id..