My passport 500gb problem!?

details here

i plug it to computer and computer makes the sound that always make when u plug a usb then i go to my computer and i can’t see it igo to disk management and is not there but it shows up under device manager and it says that device is working properly and i used the wd data lifeguard diagnostic and it shows up the but its says is not available and i run a quick test and says test complete successfully with green check mark thats why im comfuse whats going on here please help!

Model Number: WD My Passport 0740
Unit Serial Number: [Deleted]
Firmware Number: 1003
Capacity: 0.00 GB
SMART Status: Not Available
Test Result: PASS
Test Time: 12:33:52, January 06, 2013


Try reinstalling the drivers for the unit… also test the unit on a different computer