The person who set up your home wi-fi network would be the one who knows the password. Or you could do a complete factory reset of the router, and then set up your home wi-fi network again (see the router's manual for those instructions).
my mistake. it's really public wifi anyways, i just get cords for my tablet so i should left them on it or unplug for a while? two cords.. one is for usb (battery re-charging) and other one is DC V5 (AC Adapter)
I'm sorry--I'm not quite sure what you're asking about the cables. Are you asking if it's ok to leave the tablet plugged into a wall outlet constantly? And are you sure the USB port is for charging? Tablets that have a DC port for charging usually don't charge from the USB port as well--the latter is probably just for data transfer.