Hello. We are sorry for the inconvenience. It seems that the domain in question was expired at the time this post was created and could have been the reason the site was inaccessible.
For future reference, the best way to preserve your domain is to set up auto-renew. I have also attached this help file to assist you step by step on how to renew an inactive domain within the Renewal Grace Period: https://www.dynadot.com/community/help/question/renew-domain