title: Error: "'FileName.docx" has been damaged and can't be opened'" in Windows Phone 8.1
body: <p>I am trying to open documents but getting error. How do I resolve it?
  This is headache for me, Any kind of document is not opening in my application.
  I am trying to open PDF file using "PDF Reader" but getting error like this:</p>
  
  <pre><code>"Unable to Open"
  </code></pre>
  
  <p>Please suggest me.
  See my code below.</p>
  
  <pre><code>string file = "test.docx";
  IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
  
  if (isf.FileExists(file))
  {
       isf.DeleteFile(file);
  }
  
  var filerun = await ApplicationData.Current.LocalFolder.CreateFileAsync(file);
  StorageFolder folder = ApplicationData.Current.LocalFolder;
  StorageFile fileopen = await folder.GetFileAsync(file);
  await Launcher.LaunchFileAsync(fileopen);
  </code></pre>