Limited or no connectivty

Hello, I was on the internet for about a day or two on my e-machine laptop using LAN wireless connection. But then suddenly it started saying limited or no connectivuty and i coudn't go on the internet anymore. this problem had suddenly started happening to all of the laptops in my house and none of them can connect to the at&t modem in the house. when i click repair connection it does good until it gets to renewing Ip address then it stops working. i don't know what to do i need help.