External Disk Drive Shows Up In Device Manager, But Not In My Computer Or Disk Management

I have an external hard drive that wasn't showing up anywhere on my computer, so I replaced the hard drive case and now the external hard drive is found in device manager, but not in disk management or my computer. I am running windows 8, and there is data on the external hard drive that I would like to have access to.

The disk drive that is in the case is a Samsung HD103SI

I have used the rescan command in disk management. It showed as Disk 2 Unknown and not initialized. (Please note this is not a new disk and it has data on it that I am hoping to retrieve).

Some information that might help:

The system is:
LENOVO 90B70019US Lenovo H50-50

Using Belarc Advisor the drives show as:
MATSHITA DVD-RAM SW840 [Optical drive]

ASMT 2115 USB Device [Hard drive] -- drive 2, s/n 00000000000000000000
ST1000DM003-1ER162 [Hard drive] (1000.20 GB) -- drive 0, SMART Status: Healthy
WDC WD10EZEX-60M2NA0 [Hard drive] (1000.20 GB) -- drive 1, SMART Status: Healthy

Any help would be greatly appreciated. Thank you

 

Just to be sure...
Is the replacement HDD case USB powered?

 

It has a power cord and a USB cable, both are plugged in.

 

Sometimes we overlook the little things.
Is the smal switch at the back of the Ext. HDD case turned on? The on/off markings aren't always that clear.

 

Yes I have turned it on and I hear it when it spinning when I turn it on.

 

Make sure the drive is active and try changing the drive letter. That's in Administrative Tools >> Computer Management >>Disk Management. Highlight the drive you want ( it may show as *cringe* unformatted.) Then: Action >> All Tasks.
May need to shutdown the pc, unplug the USB and power from the external, reboot, plug in the power to external, wait for it to spin-up before plugging in the USB again.
Of course, don't format!

 

Since I'm curious: What's the history of this external drive? You said it wasn't recognized before you replaced the external case, do you remember anything that might have happened that could have caused that? Was it always an external drive, or did it used to be internal to another computer at some point?

Do you have another computer you can plug the drive into, to see if it does the same thing there? If not, try another port on the current PC.