I've been using the school wifi for a while, since I take notes on my laptop in class, yet when I come home and fire up my laptop, it won't connect to the wifi at my house. Even after I've deleted the entry for the school wifi, the service won't recognize my wifi and still claims 'disconnected from School_Wifi.' I've tried restarting the service, the machine, the adapter, yet nothing works.
Try re-installing your network manager:
The above commands are for Unity/Gnome. Other desktops will require different packages.