Windows 7: HDD not showing on my computer

i work on Dell, Windows 7, 64 bit. i use to work with my HDD perfectly until once my computer booted but my HDD did not show up... when i feel it i can see that it is working but the light isnt even on?
i tryed pluging it in to other computers it worked fine but it just does not work on my computer??? i need help please!!!!!

Am I correct in assuming this is an external USB drive?

yess it is

Try plugging into another USB port.

Plug in the external HD, type Disk Management into start search box, rightclick to Run as Administrator.

In Disk Mgmt, look for the external HD listing to see that it has a letter. If not give it one: Drive Letter - Add, Change, or Remove in Windows 7 - Windows 7 Forums

If it has a letter, then click Start>Computer, rightclick on the External to run Disk Check.

If HD is not detected or will not run Disk Check, install and run free Partition Wizard which may see the HD, give it a letter if not one, then rightclick on it to Check File System.

i am sorry but it still does not work

It's hard to give you further steps with so little feedback to those given already.

Is the external detected in Disk Mgmt? Is it detected in Partition Wizard? What happens if you run Disk Check or Check File System in either?

I have a similar problem - I have a SATA External Hard Drive plugged into a comparable USB port and although I can see the drive under "Devices and Printers," it is not listed under my computer along with the other drives. When I tried to change the drive number (it's listed as Drive 1; below drive 0), I right-clicked but did not get the option I get when I right click on the other drive letters (i.e., the option to change the drive letter). Any thoughts/help on this is greatly appreciated...

Try plugging it into another port - front, back and sides.

If it won't show up in Windows then install Partition Wizard, rightclick on the drive to Check File System. This can often repair the external enough that it pops up in Windows. But you may need to give it a drive letter first in the PW program.
How to Check File System? Partition Wizard Video Help.
How to Change Letter with partition manager - Partition Wizard Video Help.

Hi, thanks again for responding so quick. I tried Partition Wizard, but was unable to change the letter or check file system (I located both, but they were not highlighted; that is the links would not work for the drive I'm having trouble with).

It would allow me to do a "surface scan." I'm not sure that would help, though. I would look into a data recovery option, but even with those, I think you need to be able to designate the drive and currently it does not have a letter...

I would run the Surface Scan with both boxes checked to see if it finds corruption, then try assigning a letter again to see if it will Check File System (same as Disk Check).

The only other way I know to run the manufacturer's diagnostics/repair extended CD scan which can repair a HD is to install it into a laptop or use an adapter cable to plug it into an internal IDE or SATA port. Someone else may know a bootable repair scan or you can try Hirens or Ultimate Boot Disks which have quite a few choices for HD repair.