Nine times out of ten, people online, asking for wireless router passwords are looking to connect to a wireless internet connection that they do now own.
However, if you are, in fact, the owner of the wireless network, then as anonymous1 states, the password to connect to the wireless network should be available on the admin console of the router. You will need the admin password to connect to it.
As a last resort, reset the router to factory defaults and re-setup your wireless network. Your router's manual should provide you with instructions on how to accomplish this and what the default admin password is.