You can open it with Camera Raw either from Bridge or Photoshop as well as with Lightroom. There are other applications that can read DNG but it depends on what you want to do with the file.
Details about your setup are needed. (Such as the make and model of the camera, why you converted the raw file to DNG, your version of Photoshop and Adobe Camera Raw plug-in, etc.)
Please read this post by a forum host for advice on how to ask your questions correctly for quicker and better answers: