That depends on the modem and router settings. If you are using cable modem (a box connected to the cable from your internet service provider) without a router, you will need to set your computer to get a IP address automatically and restart the modem. Then you can renew the IP address if necessary. If you are using a router (another box) connected with the modem, then you might want to connect to the router by using the IP address on the same subnet as the internal interface of the router and enable DHCP. Then you can restart the modem and get an IP address for the router (usually you can see a button to click for that on the management page of your router after you open that in your browser, check the manual of your router about details). After that you can reconfigure your computer to use dynamic IP address and then renew IP address or restart. Please don't hesitate to post if you have questions.