IP banned??
You on static or dynamic IP? If dynamic, try turning of your router for 10 or 15 minutes, then turning it back on. Your ISP should give you a new IP during that time.
If you have no router, do the ipconfig /release and ipconfig /renew trick thats posted here.
If youre on a static IP, log into your ISP login page and see if you can get a new IP, or else use a neighbor's connection if you're on wireless... otherwise, your screwed
:-D