[MovedGoalPosts]

Reformating the PC seems a rather drastic solution, but does ensure you are getting things back to "clean" settings in case something odd is corrupting it.

Before going down that route lets check you have the basics. Sort out connections wired first before trying to get the wireless stuff going.

Ignore the router for now, and try and connect direct between the PC and Modem wired: Power everything off. Unplug the USB cables from modem and PC. Plug in ethernet cable from modem to PC, power on Modem and let settle, power on PC. Do you now have an internet connection?

If you don't have a connection, is the ethernet card in your PC enabled? If not, enable it, power cycle everything and try again.

If your ethernet connection on the PC is enabled, but you can't get a connection, try just connecting the PC wired to the router (forget the modem). If you power cycle the router and PC you should be able to browse to the router's admin pages - check the manual for the specific IP address.

Let us know the results of the above.