WD 1TB external hardrive wont connect!?

My Western Digital 1TB external hardrive worked perfectly fine for the past 2 months. Yesterday I move my laptop, It came unplug so I plugged it back in and my computer froze. I restarted my computer and now my hardrive wont connect to the computer. The light on the hardrive turns on when i plug it in (it usually blinks when I plug it in then turns on) I hear a tone on my computer that says i plugged it in to the usb port, but it wont recognize the device. so i cant do anything with it? any idea how to trouble shoot this?