why does my laptop (with Centrino) suddenly no longer recognize any available wireless networks.?

Answer 1

The wireless card may have been turned off, the software drivers for your wireless may have become corrupted, your internet provider may have cut you off or be having technical difficulties, you may not be able to get an IP address because they are all being used, or your router or modem or whatever you are hooked up to may be down. First contact your internet service provicer for technical support. If they say it must be your equipment try unplugging each connection device, counting to 20, then reconnecting everything. Wait about 5 minutes, then reboot your laptop and see if it now finds an available wireless network. If you did not purchase internet service, your connection may have been to someone else's internet service, and they may have turned it off or put in security that keeps outsiders from freeloading off of their expensive internet connection and slowing down their connection speed and gobbling up their bandwidth.

Something has changed, that much is certain.
Do you have kids?

Calico.Kitty

Answer 2

is your wireless card on?