Try updating your browser or clear your browser's cache & cookies. You can also check whether your browser extensions that block ads are affecting video playback. As another option, try opening YouTube in an incognito window with all extensions disabled and check if the issue continues.

Once deleted, these videos will not be recoverable via YouTube. YouTubers will only be able to re-upload videos after modifying their content. Viewers who want to watch deleted YouTube videos will have to use the Wayback Machine or Google search operator to try to find them.