If you forgot or lost the password that you use to connect the Internet (With ADSL, cables, or other ISP account), you still have a chance to recover it, if this password is stored in your Windows operating system or in your router.
Here's a list of 4 methods to recover your ADSL/ISP password:
If you use Windows operating system to connect the Internet (with PPTP, LT2P, or PPPoE), you can use the Dialupass utility to recover your ISP password. When you run this utility, it can instantly recover your password, as long as the password is stored by Windows.
If you got an email account from your Internet service provider, and the same password is used for both email account and the Internet connection, you can try to use the Mail PassView utility to recover your ISP password. If this password is stored by popular email software, like Outlook, Outlook Express, or Windows Live Mail, Mail PassView will be able to recover it.
If you use a router to connect the Internet, you can try to use RouterPassView utility to recover the password from the configuration file of your router.
In order to use this utility, you have to logon into your router, go to the backup/restore section, and choose to backup the router configuration into a file. After that, open the created configuration file with RouterPassView utility. If the config file of your router is supported, your password will be recovered instantly.
If you use a router to connect the Internet, you can also try to use the AsterWin IE utility. This utility is quite old and was written many years ago in Visual Basic 6, but it still works with the latest version of Internet Explorer.In order to use this tool to recover the ISP password from your router, you should logon into your router, and then go to the router page that contains the ISP or ADSL logon details. after that, run AsterWin IE utility and click the 'Show Internet Explorer Passwords' window. This trick will not work for all routers, because some routers deliberately blocked this recovery option, from security reasons.
Find all tools at:
nirsoft
Source:
Source
Other way use can use :
ADSLPwd