Are you running a static or DHCP assigned address?
If DHCP you will need to clear out the entry for your computer in the DHCP server.
If static you goto the network properties page for the connection you are using.
im going to assume he got blocked on some game or fourm or voip server. to change your external IP unplug your dsl or cable modem while you sleep and when you plug it back in in the morning it should have a new ip. assuming you do not have a static IP wich i doubt you do. if you do need to change your computers ip then go to network and sharing center - change adapter settings - double click on your lan card - double click on tcp/ip 4 - in that window is where you enter your ip address. if its greyed out then its a dynamic ip using dhcp and you do not change it in there. if you see numbers then you can go ahead and change it. if you wan to refresh your ip from your router (this is if the tcp/ip is greyed out) then go to start, type cmd in the search box, right click on cmd at the top of the search results and run as admin. in the box type ipconfig /release [hit enter] then type ipconfig /renew [hit enter]. done