The drive cannot find the sector requested - External hard disc is not working

[allenarun]

My 1TB Western Digital External hard disc is not working. My laptop switched off suddenly while copying files. After restarted my laptop, when I try to open my External hard disc drive(G:\) I'm getting the message as

"Location is not available

G:\ is not accessible
The drive cannot find the sector requested"

The Properties of the drive shows as
Type: Local Disk
File system:
Used space : 0 bytes
Free space : 0 bytes

when clicking My computer->Manage->Disk Management(under Storage in left side), I can able to see my External hard disc drive(G:\). The File System shows as "RAW" before it was NTFS, % Free as 100% but I got around 1TB data. Also I checked in different laptops but it shows the same error.

And finally I checked with "Data Lifeguard Diagnostic for Windows", it passed the test.

I'm so afraid about my datas stored in the hard disc. All my projects, photos and many important files stored in that hard disc. I dont know what the problem is. I cant find any solutions in Internet. Please help me to solve this problem. Thanks in advance.

[HappyAndyK]

MSDN explains the cause for this The drive cannot find the sector requested message as:

The disk or floppy disk may be damaged, unformatted, or not compatible with the operating system.

It recommends the following:

Retry the command after you do one of the following:

(1) make sure the disk is properly inserted;

(2) use the Chkdsk utility to check that the disk is not damaged;

(3) format the disk or floppy disk for the appropriate file system (realize that when you format a disk, any information that was previously on the disk will be erased);

(4) check to make sure you do not have a high density floppy disk in a low density floppy drive.

Or else check it the drive itself is defective and contact the manufacturer if need be.