My friend has router, I told him to download Port Magic to play JJ2 and he did it. But he has to type his username and password and he doesn't know them. He also tried admin as username and password and admin as username and an empty password but it didn't work.

What can he do?

Reset the router, assuming that this won't anger your friend's parents.

How can he reset his router? =P

With the magic button that says "reset" next to it. It's probably a small hole on a side somewhere that needs to be pressed with the tip of a pen or something.

That button usually doesn't reset the password. Try a blank username and "admin" for the password, and if that doesn't work he should ask his parents for the password.

He tried everything you said, even asking his father. His father said there is no password (blank) and the username is admin, but it's still incorrect. =(

Port Magic may be incompatible then. He should access the configuration directly instead.