not at all wierd - pretty commonplace actually.
normally (ha! - wireless is never normal ... ) can see router ... can't connect is down to the wep key ... or sometimes the ssid ... or possibly the chanel
did you or someone reconfig your wireless at about the time everything went off?
if no joy there start with a wired connection .... check that each device that won't ... will with a cable.
then with all devices in the same room as the router .... try connecting each device individually ... and then add another ... and another.
then you can go walkabout with one of the lappys see if and where the cutoff is in different parts of the building