Blue Screen on Portable HDD

Hello,

Hi,

I have set up xp on my external transcend hard disk.but Later I realise my processor was not working good.
But My hard disk showing now Blue screen of death.When started my pc using internal hard disk I have plugged that HDD In PC it shows in safely remove hard disk option but nto shows in My computer.
Please tell me how to format my hard disk or how can I reuse that hard disk.
Thanks