I hope you can get your stuff back. It happens to everyone at some point, and if you've been digiscrapping for many years it will have happened more than once probably. what determines if you can get your data back is usually whether it is a mechanical reading issue, or truly a disc corruption issue. Even if part of the disc is corrupted usually some of the data can be rescued.
What brand of EHD was it? I've had several brands over the years, but my favorites for longevity and durability have been Seagate. Seagate does offer a recovery program on their website that works well. It isn't cheap, but it isn't outrageous at $99 either. At least that is what I paid for it when one of my EHDs with digital photos on it started acting up badly. I was able to retrieve 99% of my photos from the drive with it, so I consider it well worth the money. I've used it several times since I got it for other recover operations too.
Seagate has a pretty good warranty on their drives I've learned - if it fails within 1 year of your purchase they will retrieve your data and replace it. You have to have registered it with them, and you can't open the drive to try and fix it yourself either before sending it to them. I wish I had taken the time to register my last EHD that failed - lesson learned there!
Sometimes the tech desk at the office stores will help you out and can at least tell you whether they think the data is there and could possibly be retrieved after they look at it with their high end recovery software. It helps if you bought the drive at their store (makes it easier to ask them at the very least), but if they aren't busy they will sometimes help if you ask nicely
Staples has helped me out with this.