You need to reset and reconfigure router
please follow the steps to reconfigure router
RESET THE ROUTER:
1. Make sure router is connected to power supply and is on while you perform the task below. At the rear panel of the router, near the antenna, there is a very small round pinhole that contains the reset button.
2. Using a pen/pencil/paper clip, hold the reset button for 60 sec. so that the test light starts flashing.
3. After few seconds when the test light stops flashing. Turn off the router and turn it back on after a couple of minutes.
RECONFIGURE THE ROUTER:
1. Please remove all the connections from the router. Connect power to the router and then connect a cable from the computer into any of the 4 lan ports on the router. Make sure the modem should not be connected to the router or to the computer.
2. Open up the Internet Browser (Safari, Internet Explorer, Mozilla Firefox, Opera, etc.).
3. Put http://www.routerlogin.com/basicsetting.htm
in address bar.
4. On the basic setting page scroll to the bottom and click on Apply.
5. When prompted for Username and Password, please enter 'admin' for the Username and 'password' for Password.
6. Click on lan ip setup under advanced.
7. Change the lan ip to 192.168.10.1 and under use router as a dhcp server change the starting ip as 192.168.10.2 and ending ip as 192.168.10.51, click apply and click ok for any popup message that arise.
8. Once the browser display some error message like CANNOT FIND SERVER, ACTION CANCELLED etc, Connect the dsl modem on the wan port of the router and restart the computer.
9. Power off the dsl modem and the router after making the connections.
10. Power on the dsl modem and wait till the dsl light comes on, then power on the router.
11. Open a web browser like Internet Explorer, Mozilla Firefox or Safari.
12. Access the router (http://192.168.10.1
13. Login to the router (Username = admin Password = Password).
14. Click on Setup Wizard and then select "Yes" and Click "Next" on the detection window.
15. It should give you a "Dynamic IP Detected" or "pppoe detected"(type the Username & Password of your dsl account in case of pppoe detection) and then click next.
16. Click Apply.
17. Logout of the router.
18. Open up another browser window and try to access internet.