External hard drive gone bad

PROBLEM:
I haven't totally written it off as dead, but my back-up external drive that holds 500gigs won't power on now.  I made a back-up of all the data maybe a month ago, but there are some things I must have missed.  In case I can't power it on, is there a way to read it if I take it apart, or something?  The brand is probably Western Digital, since it has WD on it.
-- Doug

SOLUTION:
If it's worth the expense, you might send it to http://www.gillware.com/, a company I've used successfully in the past.
I don't know what those WD drives look like on the inside, but you might be able to use something that I use.  It's a USB2.0 to IDE & SATA cable by Cables Unlimited.  I just depends what sort of connections that drive has available once you pry the cover off.
If/when you recover your most precious files, try this:  Online backup system called Nordic Backup.