Could have been disabled - contact youtube and ask if they can give you an embed code to help video work properly. Hope it works soon.
Youtube sometimes disables embedding by default if the video has copyrighted material on it. Inconvenient, but at least they don't go on a deleting rampage anymore.
Or better yet - find another video platform. Most of the time, any video you can find on Youtube is located somewhere else in the web as well.
Embed the video again from YouTube to your website, maybe there is something has changed, such as URL.