If you are looking to create or edit an EPUB file (such as fixing a file that might be named 461708ctpdflbrnld), the following tools are commonly recommended:
Apps like Moon+ Reader are often used for managing and reading EPUB files. Creating and Managing EPUB Files 461708ctpdflbrnld epub
An EPUB editor that allows you to perform a "sanity check" to ensure all tags are closed and the file is formatted correctly. If you are looking to create or edit