I forgot my passphrase and when I try the manage

well theres many ways to fix this. form teh info you have provided i am assuming by passphrase you mean the key that allows you to connect to your wireless network. no passphrase has a default set to admin. the only default hing with routers that is set to admin is there setup page the first ime you loginto it. yoru passphrase was setup by you or someone else and that is unique to you. two ways of resetting it is logging into the router using you web browser while plugged directly into yoru router or hold the reset button on the router and that brings your router to the default factory settings.