Try going to acer's support site and updating the chipset for your particular model. Refreshing the chipset can help to kick start the usb controllers. If that doesn't work, it is probably something hardware related, i.e. the controllers on the motherboard are damaged due to heat or something.
Thanks for the reply
i did upgrade the chipset ( from acer support website ) still doesn't work. I think it might be as you've stated. Could be because my laptop is is on for long hours everyday