Can a 5v battery charger be used to charge a 3.7 v battery?

Last night I took my zen vision w which has a 3.7v battery and i tried to charge it with a 5v usb wall charger. At first it was charging normally, my zen even turned on, when I came home from walking the dogs my zens screen was black and the blue light just flashed five times every time i tried to turn it on. So I guess the answer is no, i guess i blew a cuircuit. I feel horrible...