Here is the simple way to release and renew IP address, if the IP address of your computer is assigned by DHCP server set up in your network.
1) Go to Start and click Run.
2) Run window will appear. Type cmd and click OK.
3) Command prompt window will appear. Type ipconfig. You then will see the IP address and other network information of your network card.
4) Type ipconfig /release to release the IP address.
5) Finally type ipconfig /renew to get new IP address.