I honestly know eff-all about Windows 8, but assuming it's not going to be too far removed from Win 7: you should be able to check in the "networks and connections" tab to see if you have a working broadband connection. If you don't, a little X should be shown over a tiny computer in the right-hand side of the bottom of the screen. That would indicate a "broken" connection, ie the internet is not working. There would also be (in the networks tab) a picture of a PC, a house and a world, with a line going through to each. If there's an X over that then the internet conenciton is not functioning. You should be able to go into networks, select your connection and try to make it connect.
What cable was put in that is messing you up now? Was it put into your computer or into the apartment? It couldn't be something as stupid as one of your flatmates unplugged the broadband to plug in this cable, could it?
