|Troubleshooting USB device problems including for flash drives, external drives, memory cards.|
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"The light of the external hard drive is on, however, there's no whirring or any sounds, or blinking lights whatsoever."
"it still won't read when i tried it on another pc,..."
An external hard drive must be plugged into a USB port it can get 500ma from. It should work when connected to a USB port that's built into the mboard, if not elsewhere - the ports built into the laptops base, or the ports on the back of a desktop computer where most of the ports are.
The external enclosure may be damaged, or the hard drive may be damaged. The hard drive must spin. It can be hard to tell if a laptop sized (2.5") hard drive is spinning when it's in the enclosure - they make very little noise.
"I have already done the steps that was posted on this forum for using the TestDisk, but it says structure is ok,"
How and when did you do that? Did you do that before or after you couldn't access it in My Computer ?
If Testdisk could and can find it, the hard drive enclosure's circuits and the harddrive are probably okay, your problem is just that the drive doesn't show up in My Computer.
The data on the hard drive may have damage that Testdisk didn't detect - there are other programs you can try.
You could remove the hard drive from the external enclosure and connect it to a desktop computer by using an inexpensive adapter (don't boot from it on the other computer- it's common for XP to NOT load Windows all the way if the mboard hardware on the other computer is more than a little different), and test it with hard drive manufacturer's diagnostics, and otherwise see if you can access it normally, or you could install it in a different external enclosure, however, I've found you can't run hard drive manufacturer's diagnostics on a hard drive that's in an external enclosure. (You can't boot from a drive that has XP on it when it's in a USB connected external enclosure due to Microsoft not allowing that.)
"guess the easiest way is to format the hard drive, huh? even so, is it even possible to reformat it if the hard drive cant be read?"
That's a last resort. You probably don't need to do that.
If the drive enclosure's circuits show up in Device Manager as a USB mass storage device under USB Controllers, and if the hard drive model shows up in Device manager under Disk drives, and if the hard drive shows up in Disk Management, then your only problem is you can't access the partition's data in My Computer or Windows Explorer. Try another program other than Testdisk to see if you can repair the data damage.
If that doesn't help....
In that case, in Disk Management, you can delete the partition(s) on the drive, make a new one, or more than one, and format it, or them, and the drive's partition(s) will then show up in My Computer and Windows Explorer.