NetworkManager not showing or connecting to wi-fi networks

[Adam Funk]

Hi,

My son's laptop, which worked fine yesterday (& was left on but
suspended overnight, as usual) has a weird problem today.  In the
lightdm screen & when logged in, the NetworkManager applet doesn't
list any wi-fi connections (there should be at least 1, sometimes 2,
where it's sitting --- wi-fi is working fine on other computers in the
same room), and when we try the "Connect to Hidden Wi-Fi Network"
option & select the one in this house, the applet lines go up & down
for a minute, then it fails to connect.

It's hard to get diagnostic information off that machine since it
isn't networked, but if there's something specific I should look for,
I can try.

I used lshw -C network and lsmod to check that the right driver is
loaded, them tried rmmod & modprobe to reload it: same problem.  I
tried sudo ifconfig, ifdown -a, ifup -a, and several reboots: no
success.

Any ideas?

Thanks,
Adam