I suspect the Router.
Try another laptop or pc. If they connect then the problem is on your PC else its the router.
Make sure your cable is working and that it is a Straight cable not a corss-over.
Take both points of the LAN cable and hold them side by side. The colors must be in the same sequence.
There should be a reset button at the back or bottom of it, reset it. Beware, that all your custom settings on it will be lost as set to default. If you haven't changed settings on it in the first place then go ahead.
Hope this helps

Grant