Hard reset TP-LINK TL-WR840N

Factory reset (Hard reset) The reset button is located on the back and is labeled WPS/Reset. Power ON the router, press and hold the button for more than 5 seconds. You should see the System LED flash more quickly than before. Release and wait for the router to reboot – it might take a minute or two. PS. The System LED is located on the front panel – it is the one that looks like a small gear wheel.
Firmware Firmware link
Default username admin
Default password admin
Default IP address