the only way is to hard reset the router if you forgot the login password for most cases. now some of tplink routers have a password recovery function, http://www.tp-link.com/en/faq-1550.html

-Default usernames and passwords are specified in the documentation that accompanies the router. The default username and password are marked on a label along with the router’s serial number and login address.
-Reset the router
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-Reset the router
Go to "http://192.168.1.1" or "http://192.168.0.1" then go user d efault usernames and passwords

You have two options:1)If you're still connected to WiFi but don't know password you can find password in your PC/Android(rooted)Do Google: "how to find WiFi password in Windows/Android"Or alternatively you can go to tplinklogin.net or 192.168.1.1, log in and find your password there.2)Reset your WiFi router and set new password from address mentioned above

The default pw is written in behind of the router device.You just login http://192.168.1.1 with this pw and change on this.

You can reset and reinstall. Access the http://colorswitch2.com to see more

i'm go to http://192.168.1.1 but not know user name and password, how to know it?

Tried to do the same thing for my comcast router but the router login IP was different it was 10.0.0.1. Rest all process was same.