Internet connection problems

Hello,
Ok first off this is driving me MADD!!! Out of the blue, last night, my laptop refused to connect to the Internet. Basically I can connect to the wireless network which I've confirmed with my brothers laptop can connect to the Internet, but I can't. And looking at suggested remedies and trying them all, I'm still in same situation. I've tried restoring it, I've turned off my firewall, I've restartd the router (which so happens to be a router and modem all in one) and I've tried the cmd entries still nothing (although I wouldn't mind running them again),at the moment, all ip and DNS settings are set to automatically detect, and in my network map, it calls the wireless network unidentified , even when right below it has the name of my network in brackets under connection. PLEASE CAN SOMEONE HELP ME cos I'm this close to making my laptop subject to the laws of gravity from my 27th floor balcony!
wrt my operating detals, I'm on vista, laptops a sony vaio vgn-fz38m and i'm with BT broadband. Thanks and hope to hear from someone soon.