Need a little help here

I have a WD 500GB external hard drive that is not being recognized by my computer anymore. It just stopped working. When I plug the USB cable in, Windows recognizes that the device is there, and says that it has installed the approapriate software for the device and it is ready to use. However, the drive does not appear in My Computer. in the disk management i can see my own internal disk which is disk 0 and external disk (disk 1). And it show You must initialize a disk before Logical Disk Manager can acess it  but although i choose both MRB or GPT it does not work with a error the request could not be performed because of an I/O device error …my friend aks me to try TestDisk but i don know how to use it…who can teach me what should i do?

For help with testdisk you need to use Google and youtube

you will find FAQ’s and tutorials