Have a look at the literature which came with the router. Connect computer to router with ethernet cable (one in the carton the router came in). You can also download the setup literature or the full router manual from the Netgear home site.
Once in the router's user setup screens, go to wireless security and renew wireless security passphrase. Log out of router. Apply password to windows networking (or the wireless adapters own user interface).
Disconnect ethernet cable. See if you can connect to the router user interface again, via wireless this time.