Hard reset TP-LINK TL-WR841ND

Factory reset (Hard reset) With the Router powered on, use a pin to press and hold the RESET button hole on the back of the device. Hold for more than 5 seconds, release and wait the router to reboot to its factory default settings. Second option – hold the button for between 8 and 10 seconds and then release.
Firmware Firmware link
Default username admin
Default password admin
Default IP address 192.168.0.1 or 192.168.1.1