I'm not sure why you are fixating on the IP address if you are trying to setup a router
It should simply be a case of powering off the modem, unplugging any ethernet or USB connections you've had between your computer, connecting your router's WAN (internet side) ethernet port to the modem, and a computer to the router's LAN (network) port, power modem, let settle, power router, let settle, power computer.
The modem cannot recognise that there is a new device (computer / router / whatever) without it and the device connected to it being power cycled.
If you've been fiddling a lot with the router's settings, try restoring to factory settings, before you do the above.
If you still have problems, please confirm the type of modem you are using for your cable connection, and the type of router you now have. Also indicate if you are able to browse from the computer to the router's admin pages, and what the router is exactly saying in terms of it's lack of connection.