WD my passport unusable

my external hdd got some problem.it can be detect but unable to use it…i bought the passport is 500gb…but it showed 0mb…before this,because of my computer lag…so i unplug it without safely remove…then i tried in other computer same problem occur~
at first,when i plugged in it will make my whole computer lag…when i open my computer to view my hdd,it will become no respond…until i unplug my hdd…what is this problem?

dixon_wd,

The described behavior could be attributed to data corruption. I would recommend changing the USB cable, then proceeding to test the disk drive using Western Digital Data LifeGuard Diagnostics for Windows in order to confirm S.M.A.R.T. status and overall drive health.

Additional information is available in the following link:

http://wdc.custhelp.com/app/answers/detail/a_id/940/