John, I have no idea who manufactured these window blinds; however, I assume you have the pleated shades and not the newer MCD shades. If it is the MCD shades, you can contact them at: WWW.mcdinnovations.com
or at 800-804-1757.
Now if you have the pleated shades, you'll have remove them first by opening (raising) them completely.
Next, grab the shade from both sides and gently rock them back and forth - towards you and away from you from there tops. They just click in to there mounting brackets.
Once off take a look at the top of them. They should be marked with there dimensions and a number such as W811. Give these to your dealer and he should be able to get you exact replacements.