You should follow these steps:
1) Power down all computers, the router, and the modem, and unplug them from the wall.
2) Disconnect all wires from the router. Wait 30 minutes.
3) Power up the router and allow it to fully boot (1-2 minutes).
4) Press and hold the reset button
for 30 seconds, then release it, then let the router reset and reboot (2-3 minutes).
5) Power down the router.
6) Connect one computer by wire to port 1 on the router (NOT to the internet port).
7) Power up the router and allow it to fully boot (1-2 minutes).
8) Power up the computer (if the computer has a wireless card, make sure it is off).
9) Try to ping the router. To do this, click the "Start" button > All Programs > Accessories > Command Prompt. A black DOS box will appear. Enter the following: "ping 192.168.1.1" (no quotes), and hit the Enter key. You will see 3 or 4 lines that start either with "Reply from ... " or "Request timed out." If you see "Reply from ...", your computer has found your router.
10) Open your browser and point it to 192.168.1.1. This will take you to your router's login page. Leave the user name blank, and in the password field, enter "admin" (with no quotes). This will take you to your router setup page. Note the version number of your firmware (usually listed near upper right corner of screen). Exit your browser.
If you get this far without problems, try the setup disk (or setup the router manually, if you prefer), and see if you can get your router setup and working.
If you cannot get "Reply from ..." in step 9 above, your router is dead.
If you get a reply in step 9, but cannot complete step 10, then either your router is dead or the firmware is corrupt. In this case, use the Linksys tftp.exe program to try to reload your router with the latest firmware. After reloading the firmware, repeat the above procedure starting with step 1.
Resetting one’s LinkSys default password becomes especially important if you have forgotten the password that you had set before. The default password is the factory one. To restore the factory settings of your LinkSys router, hold on to the reset button on the unit for about 10 seconds or more and then release it. It’s usually that simple. You will know that the unit is ready as soon as the lights stop blinking. If you had changed the password, it will have gone by now and you may now refer to the user manual for the router to proceed further. If your router is configured as per your ISP settings, you may end up losing connection until you set up the unit again. And once you have managed to do that, it will be prudent if you could log in and reconfigure it again. This is done in order to secure the LinkSys router. For you to reconfigure the router, you need to connect it to a PC through one of its Ethernet ports, and then load a web browser, and then go to this URL: http://192.168.1.1/.
That takes you to the pop up box and you will be required to enter your password and username to log on to the router. The LinkSys default password for the older routers is “admin” (remember using lower cases only). The username is blank. For newer routers, both the password and the username are set as “admin”. And once you have gone past the login screen, it’s now possible to reconfigure the router. You will then need to go to the management tab and change the administrator password to something that will be both easy for you to remember and hard for others to guess. You will also need to enable your WAP or WEP security to curb unauthorized access to your wireless network.