|Typically, to reset a router to it's default you have to press and hold the reset button for about 10 seconds.|
Then, when it comes up try typing in admin as the username, leave the password blank and click on the Ok or Login button (whichever it has). If that doesn't work, try "admin" as both the username and password.
You can also read the manual/setup guide for more detailed info on the login.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.