You can go to your router setup page to view or change your network key. See your router documentation for how to access the setup page. You can also reset your router by pressing the reset button on the back of the router and holding it for 10 seconds.
This will reset the router to factory defaults. If you reset the router you will have to manually configure wireless security.
Jim
Microsoft MVP Consumer Security - Forum Moderator - Live One Care - Live Mesh - Microsoft Security Essentials