Router IP's are generally 192.168.0.1 or 192.168.1.1 Try plugging on of these addresses into your browser and see if you get the username password screen for the router admin console. If you do then I hope you remember the username (most of the time it is admin or administrator by default) and password. If you can get in to the console disable WEP and reconfigure your WEP settings from the ground up.
If you don't know where the documentation is for your router then I highly recommend that you visit Belkin's website and download the PDF file for it and keep it handy if you have to reset your router.