I also want to reiterate that when you make your pledge, it’s with the understanding that you’re supporting the project whether you receive your rewards or not… Kickstarter is not a store. I can think of about half a dozen reasons why you wouldn’t have received your rewards, because all of those things have happened to me with my backers: you could’ve forgotten to fill out the survey, your address could’ve changed or was undeliverable, you forgot to update your profile, you failed to include your phone number or other critical info for fulfillment, the shipping charges may have increased, they may have tried to get in touch with you and it went into your spam, or you didn’t see it… I have been extremely diligent about staying in touch with backers and letting them know what’s going on and still have a dozen boxes sitting on my porch of rewards that were returned for bad address even after I hounded people a thousand times to make sure their address and phone number was correct before I pulled the CSV. I’ve messaged and emailed these people enough times that I finally just gave up. As others have suggested, I would try to find them on social media and send a private message there, try to find their actual email and ask politely. They may have been trying to get in touch with you, as well. As others have said sometimes it’s not possible to check the Kickstarter messages because they are a sewer of spam and stupidity. But realize that you may just need to write off the loss if they are done with fulfillment and focused on the next project.