This guy is keep disconnected me while i play this certan game (maplestory)

He uses ddos. how do i stop him

go to the police, ddos is a crime
how u know it's ddos?

you're not serious are you?

In the US, there can be a serious federal crime under the Computer Fraud and Abuse Act with penalties that include years of imprisonment. Many other countries have similar laws.
source: http://en.wikipedia.org/wiki/Denial-of-service_attack

You're 100% right that it's a federal offense, question is, what will the police officer do when you tell him about the attack? Think about longer brah.

let's first listen a bit more to the guy before we fight with words

I bet that both guys have connection problems and because one want to excel as 'a hacker' he tells to the other guy that he's doing it

bring a party of 4-5 guys, go to his house, and beat him with nightsticks.

You forgot to mention the part in which you obtain his address.

make a gui in visual basic to track his location in real time..

DDOS Back ....