Hard reset D-Link DIR-628

Factory reset (Hard reset) Power on the router and press the reset button for 10 seconds. The reset button is located on the back of the router – it is placed in a small hole so you will probably need a sharp object (like a paperclip) to press and hold it down. Release and wait about 30 seconds for the router to reboot.
Firmware Firmware link
Default username admin
Default password [leave blank]
Default IP address