1) If the wireless card can see the router SIDD, likley the card is ok, connection setting issue likely. BTW, unlikely it's a modem issue.
2) If true, you may connect to the router using a cable and check for the wireless setting. The wireless card should follow exactly router's security settings (WPA or WPA2 recommended, not WEP). Since the router was powered down and up again, there is a possibility that something somehow changed.
3) If still no luck, you may try to reset the router to original (or factory) setting and set up wireless secuirty again. If you need help on router wireless setting, you may tell the router type and firmware (e.g. stock firmware or like DD-WRT or Tomato)。 Someone here who use the same or similar router may help.
4) To test out the wireless card, you may uninstall the card and install it again with the updated driver.
