Ubuntu 14.04 LTS USB not working (autosuspending)

To correct this, execute the following commands on terminal:

sudo su

for foo in /sys/bus/usb/devices/*/power/level;
do echo on > $foo;
done 

Extracted from http://askubuntu.com/questions/80638/how-to-disable-auto-power-off-of-usb-devices-like-usb-mouse