My router firmware is changed and I now want to go back to the stock firmware. 

- I configured my ethernet adapter ip to 192.168.0.66/24 

- Run TFTP server and give the .bin file directory

- Connected Ethernet cable from LAN1 to PC

- Turn on the router by holding the reset button for 5 sec (not WPS button)

- Now Router will make a TFTP request to the system. 

[I used wireshark application to check for the traffic. And I see there router makes a TFTP request for ip 192.168.0.6  ]

- And the firmware will be installed.

Thanks