Netgear dg384g v4

First check that you do not have capitals lock in.Then try again the following whilst you put http://192.168.0.1. on your browser.

Default: 'username: admin password: password".
or
'username: admin password: 1234".
or
'username: admin password: 'blank empty space here'".

If all the above does not work then your router had been used, and password changed, or is fault. in this case bring it back and ask replacement.
There is also a reset button at the back of router. It is a tiny hole where you stick a pencil on router startup to get reset. But if the router is new and does not get default user/password I suggest changing it, It is possibly a return, and you do not know if you get more troubles after reset.

regards