Normally, router's settings are password protected to avoid undesired changes.
Usually the manufacturer provides routers with their own factory settings.
DLINK routers are shipped with the following default parameters:
The default IP Address to use to connect to the routers is 192.168.0.1 so to connect to the router IP, the address of your computer must be in the same subnet with the device. It means that your computer should have an IP address 192.168.0.X (X is in range of 2~253)
The default user is "admin" and the related password is NULL, so left blank the password field.
To reset factory setting you have to use a paperclip and hold down the reset pinhole on the back of the router, You must hold down the reset pinhole till the power led begins to blink.
Now you are ready to enter the router with the default settings.