If you have ever taken a backup of the configuration of the router into a file,
then the free
RouterPassView can help :
The backup file of the router usually contains important data like
your ISP user name/password, the login password of the router, and
wireless network keys. If you lost one of these password/keys, but you
still have a backup file of your router configuration, RouterPassView
might help you to recover your lost password from your router file.
Otherwise, you are reduced to a brute-force attack, where the free
Router Password Kracker can help :
Router Password Kracker is a free software to recover the lost
password of your Router. It can also be used to recover password from
your internet Modem or Web sites which are protected by HTTP BASIC
Generally Routers or Modems control their access by using HTTP BASIC
authentication mechanism. In simple words, when you connect to your
Modem/Router from the browser (typically
http://192.168.1.1) you will
be asked to enter username & password. If you ever forget this
password then you will not be able to access your Router/Modem
In these cases 'Router Password Kracker' can help you in quickly
recovering your lost password.
'Router Password Kracker' uses simple Dictionary based password
recovery technique. By default it comes with sample dictionary file
suitable for Routers. However you can find good collection of password
dictionaries (also called wordlists) here & here.
For complex passwords, you can use tools like Crunch or Cupp
to generate brute-force based or any custom password list file and
then use it with 'Router Password Kracker'.