RouterPassView is a Portable Router Password Recovery Tool created by NirSoft. It works by attempting to find your Login Password and or Wireless Keys from your backup router configuration file. Note that you must have a backup configuration file for RouterPassView to read, and not every router configuration file is supported, however I have found that most of the popular older Routers are.
RouterPassView - Recovering Lost Router Passwords
Extracted Size: 92KB
Authors Website: http://nirsoft.net/utils/router_password_recovery.html
Download: You can get this Router Password Recovery Tool HERE