Question : WD external HD doesnt apper in my computer

My External HD falled in the ground this morning,when i try to use it now ...I can see it on the Device manager under Disk drives and under USB drives but i cant see it in My computer or in Disk management.

Any help would be grat,the HD includes very important data files.

Answer : WD external HD doesnt apper in my computer

Sounds like physical damage of the drive. In device manager you see mostly USB enclosure of the drive but not the drive itself. Can you open the enclosure and connect the drive as internal? The chances are low but still you can try your luck.
If the data is really important then you need to use (most probably) professional data recovery lab such as www.gillware.com or www.ontrack.com