Problem using router in HGC Boardband

I used router to connect to internet for 2 weeks and it works fine. In the past few days, it failed.

Details
- ISP: HGC
- DHCP
- Linksys router model - BEFSR41
- The internet & port lights are on
- tried to reset the router
- able to access router's setup page
- if cable is plugged into the PC directly, no problem accessing internet.
- the router works fine when it uses Netvigator and other ISP
- In the router setup, status page, the IP address shown is 0.0.0.0.

Thank you