WD external desktop HDD help!

My Western Digital external desktop HD is not being detected by my computer anymore (neither in My Computer or Device manager), I think my mom might have broken it when she put it upside down. I figured out that the USB cable is okay, but the USB interface in the external hard drive might be broken or maybe it is the hard drive itself. I have also yet to determine if the power supply cable is broken or not. I don't know how to go about fixing it. Does anyone have any suggestions on what I should do? I have been told to open the external hard drive, but I see no way to open it as there are no crevices or screws.

Also, can an external hard drive cable plug-in power supply run out?

I am using Windows Vista SP2 Home premium 32 bit.

I did some further reasoning that the USB/power supply cable interface is broken, because if it is not, then my computer should recognize my external hard drive in some way, although not being able to access it if the hard drive itself is broken. To further help me investigate, I want to ask the community if a computer might still recognize the external hard drive in some way if the hard drive itself is broken and the USB/power supply cable interface is not. If it still recognizes, than there is a chance that only the interface is broken or bother interface and HDD is broken. If interface is broken, then I will have to dissemble the external hard drive.

Can someone recommend me a case that will fit my Western Digital External Desktop HDD?
http://www.amazon.com/Western-Digital-Elements-Desktop-...