Problem with WD 1.5TB external hard drive

Not recommended to open the case of an external hard drive. If you damage some small connector you might loose the right to replace it.

Please check it:
Control Panel, Administrative Tools, Computer Management (please run as administrator; right click it), Disk Management. What is the information of your 1 TB hard drive? Is there any unallocated space?

you can purchased an external usb case from newegg.com I would first take the hard drive out so you can identify whether you need a SATA to usb hard drive or IDE to usb harddrive. Connect the hard drive in and see if it will power up.

Is the PC you've used before is the operating system is windows Xp? If you've using windows Xp before then you've plug it in a windows 7 Operating system, it means your hard disc have no problem the operating system of your PC is different than before. Try to plug it in a windows Xp operating system then recover it in there then format it in a windows 7 operating system then, the windows Xp and windows 7 try to make a network place in the connection then share the hard disc files that you've recovered then copy and paste it in the newly format hard drive that formated in a windows 7 operating system.

External hard drives don't need any program installed on your computer to run. Your operating system Windows, Linux should handle it as soon as you plug the usb in your computer. The programs included in your WD external hard drive are tools to backup your data.

If you try to hook up your hard drive to a Windows prior to XP, maybe your computer will not handle it.

It is always safer to safely remove your drive using the green arrow icon in the lower right corner of your screen. This way, the drive is shut down properly and you minimize chances of fails when you plug it again on another computer.

Hope this helps!

The disk-drive is "dying". If the WARRANTY (probably one to three years) on the W.D. drive still is VALID -- it probably is, you should contact Western Digital, and get it replaced, by exercising the warranty.

Open My Computer.
Click with the SECOND (usually the RIGHT) mouse-button on the icon for the WD drive.
Click Properties.
Click Tools.
Click Check Disk for errors.
Choose the option to let Windows "fix" the errors.

Restart the compuetr and try again. be sure that the USB cord to the external HD is NOT plugged in when the computer restarts until Windows has been loaded completely.
You can also try a different USB cable and a different USB port on your laptop

disconnect it and reconnect
if its still not working then we can try the reg fix

You need to set your boot sequence in the BIOS so that it does not include external drives. Basically your computer is trying to load Windows from the external drive instead of its own internal one. 

Your motherboard manual is going to help, if you can't manage it by yourself give me a link to your manual or tell me the model of your motherboard and i will show you what you need to change.