Hard reset D-Link DI-804HV

Factory reset (Hard reset) Turn OFF the router. Locate the reset pin hole on the back panel. Use a paper clip to press it and hold down for only about 5 seconds – don’t hold too long. Release. (You can also watch the lights on the front cover – it is time to release the button when M1 and M2 flash at the same time.)
Firmware Firmware link
Default username admin
Default password [leave blank]
Default IP address