Router prolem

Hello All,

I have a dlink wireless router, that ever time i try to connect to the internet says that the security setting don't match those found on the router. I also have a laptop which connect fine to the internet.
I have tried logging in to the router to change the settings but i have had no luck. it keeps saying my password is or user name is not correct.
Any help would be really appreciated as i have been told that i will have to format my PC and i really don't want to do that.
P.S i am also running windows vista.

Yours Hopefully

Toby Grant