Unfortunately, you can’t do that yourself—most likely the English audio track does not reside on the video you have. It’s just a copy. You have to find whomever originally recorded the video and then dubbed over the new language (or a company that sells it) and ask for a copy of the original version in English. What is the video of? If it’s a movie, the English audio track may be hidden on your copy and can be retrieved through a menu. But I’m suspecting it’s some other kind of video. Can you give any additional information?