Thanks Jonnyabc! I'll give you some of the basic steps that we usually do in order to troubleshoot our linksys router.
--If your modem is set to PPPoE, here's what you're going to do:
1. Call ISP to get the correct Username and Password of your DSL modem
2. Hardwire your router to your computer (from the numbered port of the router to computer)
3. Look for the default gateway *(if you're not that familiar with this step PM me)
4. Router still wired to the computer, let's open our browser (IE,Mozilla,Google Chrome,Safari) and we will access the U.I. or we can call it the router page. *(if you're not that familiar with this step PM me)
5. Click on the Set-up tab. Below will be the Internet Set-up, kindly choose the PPPoE settings.
6. Type in the correct Username and Password, the one that was given to you by your ISP.
7. Put a check on Keep Alive.
8. Make sure you're able to click on save.
9. Connect modem to the Internet port of the router.
10.Wait for some few secs and wallah! It should be up and runnin'
---hope this helps---