I can not get a connection to the internet
Is your computer connected directly to the cable modem from comcast and what type of connection if it is?(USB or Ethernet/LAN-its look like a telephone chord for slightly larger) or are you using a router?
First thing that you need to check is the actual modem(box provided by comcast normally the brands are; arris, motorola, webstar, samsung or linksys. Make sure the LED light on the front of the modem that say's either Online/Ready/Cable/nternet is stable or solidly lit.
Go to Control Panel and look for Network and Internet or Network and Sharing Center, on the top left hand side you will find tasks, look for manage network connection and check if you have a local area connection, right click the icon and go to Status then Details. Check if you have an IPv4 IP address(58.x.x.x or 271.x.x.x or something like that) if the IPv4 show as 169.254.x.x(where x can be number s from 0 to 254) its an invalid IP or your computer is not getting any valid IP from Comcast.