I have 12.04 LTS on a Toshiba Portege R835-P56X.
I try to connect to my home network over wifi. It connects, but I can't access the Internet. I tried resetting the router, but that didn't work. Please help!
Check if the wifi card is blocked (Terminal)
rfkill list wlan (for wifi)
rfkill list all (for wifi and bluetooth)
rfkill unblock wlan (for wifi)
rfkill unblock all (for wifi and bluetooth)
Restart the network:
sudo service network-manager restart