Hard reset D-Link DIR-665

Factory reset (Hard reset) Power On the router. Locate the reset pin hole on the back. Use a sharp object to press it and hold it down for 5 seconds. Release. … Important: If that does not work, try pressing the button and holding it down for 10 seconds, release.
Firmware Firmware link
Default username admin
Default password [leave blank]
Default IP address 192.168.0.1