Alright well try my guide if you have no router, directly connected to your computer and have a cable/dsl modem.
Before doing the below, cmd>ipconfig and right down your ip.
Open start>run>cmd.exe hit enter and type ipconfig/release hit enter again. This will disconnect you from the internet. Once you see you have lost connection, you can close cmd.
Go to Control Panel>Network and Internet Connections. Right click your connection and hit properties.
Now click Internet Protocol (TCP/IP) and click Properties. Click use the following Ip address and fill the first field with all 1's and then hit tab once. Hit ok 2 times to exit out the windows.
Right click your connection again, hit properties, bring up the Internet Protocol again and this time click obtain an Ip address automatically. Dont forget to click the bottom circle button as well. Hit ok twice to close both windows.
You should be connected again. check cmd>ipconfig and compare it with the one you wrote down. You should have a new ip. If not too bad.