DELL LATITUDE D630 - WONT CONNECT TO INTERNET

I have a Dell Latitude D630 that will not connect to my internet. All other devices work fine, including the 2 other computers. It was working fine until someone came to fix out internet speeds. They gave us a new modem and after that, it stopped connecting. We have Century Link and the speed and range is perfectly fine. When I try to connect, it says unable to connect. I've tried the troubleshooting, disabling and re-enabling the adapter settings, removing the network, and renewing ip address in the command prompt. Nothing seemed to work. Please help!!