If you never changed the router's login credentials, many use the default username admin and the default password password. Try that combination to see if it works. Otherwise, you can run a web search ...
How-To Geek on MSN
Your router has a second password you've probably never changed
Your Wi-Fi password is useless if you haven't changed this hidden router login ...
Some results have been hidden because they may be inaccessible to you
Show inaccessible results