hard drive failure?

Hi folks, I am going out of my mind an am in desperate need of help.

I use a Latitude D800 that I've had for about 6 years. The last week or so, services.exe was taking up way too much of the CPU, like hovering between 8-25%. I thought it might be malware, so I checked thoroughly and came up with nothing. Then I thought I might have deleted an important program file inadvertently, causing the computer to act strangely. Or perhaps it was malware that I couldn't find.

In any case, I decided to just reformat my hd, and replace it with the backup image I have. I used DriveImageXML to create the backup image and kept it on my 750GB LaCie external hd. My internal hd reformatted okay, and then when it came time to transfer the image, it just wouldn't do it. DriveImage came up with an error saying "the target partition has to be equal size to the partition it's loading from," or something along those lines. I was confused as I had used this particular image to restore my computer in the past.

I reformatted my c: drive again, hoping that it might make a difference. It did not. I browsed through the image file on my external drive and was able to see everything just fine.

Then, suddenly, my computer stopped recognizing my external drive. I tried reinstalling windows, since my c: drive was still blank, yet it still did not detect anything. I have tried plugging the external drive into two other computers and it hasn't been detected. I am terrified right now because this drive was the backup--all of my documents were on this drive. Normally they would be on my c: drive, too, but I had just reformatted it and was about to restore the image.

The confusing thing is that my external hd didn't feature any signs of failing. Made no strange noises and didn't seem to be slower or "skipping." When I turn it on, I hear it spinning, and I hear some platter activity while it spins up, but then no activity.

I apologize for the length of this thread but I have no clue what to do. Does it seem like this hd has failed? What can I do to salvage the data? At this point I don't care about the image, all I want are my documents that I back up regularly with a sync program.

I appreciate you reading this far, and any help would be greatly appreciated.

Thanks.