Most modern routers allow you to backup the configuration of the router into a file, and then restore the configuration from the file when it's needed.
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 your ISP password, your wireless network keys, or the login password of your router, but you have the backup file of the router configuration, RouterPassView utility might help you to recover your lost password.
However, due to large amount of router models available in the market, RouterPassView cannot support all routers. Currently RouterPassView supports a limited set of router models, and support for more routers will be gradually added in future versions.
For more information about the RouterPassView utility, click here.