Hi my HDD was accidentally drop into water. Can I still use it again because until now have not using it yet for the water inside the HDD getting dry.
Such a bad luck. Leave it alone for couple of days. Try using a hair blower to dry it up.
If that does not work then you should be looking to buy another one.
All drives are vented to the air via a breather hole (there should be a notice on the label warning you not to cover it). Therefore water would most probably have entered the head / disc assembly. 
