My linksys router is not detected my broadband?

Hello, Please tell me in details and step by step solution if you have......!

1.Internet works correctly with direct cable connection.

2. I am using linksys WRT54GH router.When i connect my broadband cable to the router then my net is not working.

There are some LED lights indicated that my internet is not detect in Router.

3.Again, At my friends house it is working properly with its broadband cable.

4.My friend is using tp link router.When i connect this router with my cable then it is working correctly.

So , things that my router is not working at my home with my network cable !!!!

Please help me !!!!