PS3 Attempt to obtain Ip Address Timed out?

Hi a couple of days ago i wanted to change my nat type on blacks ops from strict to open, i did a bit of research and found out there was away to do this. It involved going to my router settings and for that it requires a password but i had forgotten it, it said to reset my router to default settings (I have a BT Home Hub), after i did this i could not connect to it on My ps3 at all. It just gets past putting in the WPA in then it says it has timed out trying to get the ip address. I was told that if i reset my ps3 to defaults it would work but still no luck please help?!