u r confusing

is it after you plugged in the router it stopped working, or it's after you set the encryption it stopped working?

if it's the first case, like the other guy said, you need to clone mac address.

from the original equipment you used to set up the broadband, type ipconfig/all to find the mac address.
or depends on the modem, you can go to the modem interface to find out the mac address it loves.

the latter case you got to give more details...