Linksys WRT54G router could be reset either of the following two ways:
Resetting the Linksys WRT54G router using the factory reset button – HARD RESET
This method could be used when you are unable to access the web based setup page of the
Linksys WRT54G router or in case of forgetting the Linksys router’s password.
While the Linksys WRT54G router is powered on and is power LED is blinking, press
the reset factory button on the router.
Using a sharp or pointed object, press and hold the reset button for about 30