are you connected to the router with a wire (ethernet)
press the start button
press "run"
type in "CMD" and then press enter.
wait for the black windows to appear.
in the black window type in "IPCONFIG" press enter
note down the default gateway (some thing like 192.168.1.1)
open the internet explorer (big blule e)
in the address bar type in "
http://192.168.1.1 (or whatever the address is)
you should now be able to log in.