WD EXTERNAL HARD DISK 1TB suddenly "unallocated" and "not initialized"

Hi guys. I'm new here. I've tried to read all the discussion about how to fix the unallocated hard drive but I just can't understand it as the cases were pretty much different than I'm facing of.

Here's my problem.
Yesterday my external hard drive seems normal, everything is fine, until there's a blackout and I have to put "sleep" to my laptop. After the power got back, the hard drive suddenly gone and when I check the list of drives under "Disk Management", it showed up as "Disk 1 - Unallocated".

(I've attached screenshots here for your viewing)

My external hard drive is WD My Passport 1TB. It contains a lot of valuable data I cannot afford to lose. I really hope there's a way to fix this, and once I get back all of those precious data I will buy another HD to transfer them ASAP because I cant let this happen to me again.

Your help is so, very much appreciated.
Any questions regarding my problem, let me know. I'll provide all of the details you guys need.

NOTE
1) I've tried TestDisk but on the "Analyse" process, it says "read error"
2) I've changed cable, but the situation remains the same.
3) I've tried Recuva, but it doesnt recognize my external drive.

Hi!

First don't mess up with the WD drive settings.. download partition wizard 7 (its free)..then .. open it ..click wizard(menu) .. select partition recovery wizard.. and it will find the partitions on it i think.. that way you can recover your partition that has been lost.

Hi Noor, thanks for replying. What is the estimate time for finding the missing partition? I wanna prepare myself if it's gonna take longer than 12 hours *.*

Just so you know, ive made several calls to computer service centre, they were all refuse / hesitate to take my case since it's 1TB and one of the guy claimed that if it's unallocated, the drive is lost and there's no where I could fix it -which pretty much the last thing I wanna hear right now.

it takes just a couple of mins max

Alright so I just finished scanning with Quick & Full Scan using Partition Wizard.
No good news.

Gonna try the second option. (Linux)

If anyone can help assist me through this problem, please do. I really, really wanna solve this :/

hello there Slartybart,
few questions
1) Does this mean my current hard disk (the one that I have problems with) is in a total disaster state?
2) I havent tried the linux recovery steps, but say if i do, and I found the files (hopefully), will my hard drive comes back to live when I change back my OS to Windows? Or I need to copy all of my data when in Linux?

Hi Mark.
By 'Windows system", are you referring to my data? or my hard disk?
If my hard disk is dead, then it's ok as long as I can retrieve my data back. Thats all I want.