When I plug the power source into my external hard drive I get nothing. It won't except the power cord and turn on.

Welcome to Tom's Hardware, Heathsears!

In order for us to help you out, you should give us more info on the drive itself. What model is it?
It seems like it doesn't get enough power from the power source. My suggestion would be to try with a different cable and maybe try plugging it in another computer, see if it gets recognized there.
Check the model of the external HDD and see if it incorporates hardware encryption or not.
If it doesn't have it and the different cable and computer don't work, you can take the HDD out of the enclosure and connect it directly to your computer via a SATA cable. This is a much more promising power source to get the HDD to turn on.

If none of these troubleshooting steps work, you're most probably looking at an old dead drive. :(

Hope this helps you! :)
SuperSoph_WD