My WD external drive unmounted itself and now does not work I have a strange problem. Working on an OS 10.9.5 MacBook laptop.

Last night, I was exporting a 20-something GB Aperture library from my WD 2TB drive to another hard drive. I left, and when I came back the next morning, my computer warned me that I should properly eject my hard drive. I hadn't disconnected it, and my settings are set so that the computer will NEVER go to sleep or shut down when the power supply was connected (which it was). Now, my mac won't recognize the hard drive.    


Is it dead?  
How can I prevent this from happening again?
How can I recover my files if I can't see the disk???


I've tried:


Powering my computer on and off 
Using a different USB connector
Using a different power cord
Plugging the external drive into another mac (did not work) 
Plugging the drive into a windows computer (nope)
Mounting through disk utility, or using disk utility to repair/verify the disk (got this error message: Disk utility can't repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files).
Suggestions on these sites: External drive does not mount after plug off without eject and Sometimes Mac doesn&#39;t recognise my external hard drive e.g., going through terminal to unmount OR eject OR view files in read only mode (all just say the volume timed out)  
Read suggestions on this thread about drives disconnecting on their own - wasn't sure what to do, but realized the problem might have had something to do with exporting Aperture files? https://discussions.apple.com/thread/2597920?start=120&amp;tstart=0 


This is my time machine disk, and it has some other stuff on it I need. I also don't know whether to trust my machine to plug another hard drive into it. I can't update to a newer OS just yet. I'm terrified to plug in my other hard drives because what if the same thing happens to them!? Unfortunately all my Aperture libraries are stored on external disks!

Info:

Last login: Sun Mar 26 16:39:26 on ttys000
ericaneomputer2:~ erica$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *320.1 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            319.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS NEWTON_WD               2.0 TB     disk1s2
ericaneomputer2:~ erica$ diskutil info disk1
   Device Identifier:        disk1
   Device Node:              /dev/disk1
   Part of Whole:            disk1
   Device / Media Name:      WD My Book 1140 Media

   Volume Name:              Not applicable (no file system)

   Mounted:                  Not applicable (no file system)

   File System:              None

   Content (IOContent):      GUID_partition_scheme
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 USB
   SMART Status:             Not Supported

   Total Size:               2.0 TB (2000365289472 Bytes) (exactly 3906963456 512-Byte-Units)
   Volume Free Space:        Not applicable (no file system)
   Device Block Size:        512 Bytes

   Read-Only Media:          No
   Read-Only Volume:         Not applicable (no file system)
   Ejectable:                Yes

   Whole:                    Yes
   Internal:                 No
   OS 9 Drivers:             No
   Low Level Format:         Not supported
Either your WD MyBook enclosure has failed or the disk itself has failed.

I am basing this assessment on two factors:


Points 4 &amp; 5 above - that plugging it into different computers didn't work.  If it doesn't work on different computers you have narrowed it down the the WD unit itself.  If the problem was with your Mac, it wouldn't be present on a different computer.
The correct response  provided by diskutil for disk1.  It's highly unlikely (though not impossible), that if the enclosure wasn't functioning you would at least get erroneous information back or no information at all.  The WD enclosure is reporting back that there is a drive but it has no operating system.  Chances are, it's the drive.


However, you can take it a step further and do some additional diagnostics.  The key here is to isolate the major individual components of the WD enclosure - the logic board and the drive itself.  

So, to diagnose this you will need either of the following


a known working hard drive 
a 3.5" HDD to USB adapter (I recommend this option for reasons that will become clear momentarily).


You will need to disassemble the MyBook.  From my research, the case appears to be held in place with "snaps" which you just pry off so it shouldn't be too difficult to get into.  There's a straightforward set of instructions on Instructables.com

Depending on the option you took above - you either need to change the drive in the MyBook  or plug the old drive into the USB to SATA adapter.

If one component works (i.e the drive), then you know for a fact that the other (i.e. the enclosure) has failed; or vice versa.

If it is your drive, the USB to SATA adapter will allow you to attempt to recover your files.  I have personally used Disk Drill with excellent results (it's free to use the diagnostic portion and to see if you can recover data).  You will be able to make an image of the drive and attempt recovery on the image lessening the chance of total failure of the drive.

If it happens to be the enclosure, the USB to SATA adapter will allow you to continue to use the disk drive while you come up with a more permanent solution (the MyBook is essentially the same thing but with a more elegant enclosure).

If you choose the "drive method" you will still be able to get the same diagnostic results, except you won't be able to transfer or rescue any data if it happens to be the MyBook enclosure that's bad.

Now, as preventing it from happening again - well, this is a spinning hard drive which means it mechanical.  It's going to fail.  The only thing you can do is mitigate data loss by having a backup