If you're getting prompted for a username and a password...then you are on the right track.
Netgears usually default to 192.168.0.1 ...that' the LAN IP address you need to type in to hitup the web admin page.
Netgears also usually default to admin and 1234 on the RT and RP series routers. Other Netgear models have just "password" for the password (without the quotes, and using lower case letters) You try regular keys instead of numlock pad?
So...if you're getting the login prompt...then you're on the right spot. If the standard user/pass does not work....then my guess is someone else setup that router, and has changed the default password. Which leads to the next question...is that router yours to manage?