If that is a permanent IP your only option is to use a proxy. Check out
Multiproxy. And be nice next time. Obviously someone thinks you have been
hogging their bandwidth and overloading their servers. Put simultaneous
downloads to 1 and requests per second to 1.

If that is a DHCP IP just unplug your cable/adsl/whatever for the night and
hope that someone gets your old one and you get a new one. I don't know how to
force a change with DHCP foolproof and easily, I do know that changing your
nic usually helps because it has a different mac address.