for router? go on your internet browser, go to http://192.168.1.1
and login using user: admin/ pass: admin it could also be password for the password, or no username required, or some combination of that, just play around with it. then you can change thee pass to whatever you want. alternatively, download the program Cain from http://www.oxid.it/cain.html.
install, open program, go to the wireless tab, and click the blue plus and the pass will appear.