Word.Application word = new Word.Application();
Word.Document doc = new Word.Document();
object fileName = @"C:\wordFile.docx";
// Define an object to pass to the API for missing parameters
object missing = System.Type.Missing;
doc = word.Documents.Open(ref fileName,
ref missing, ref missing, ref missing, ref missing,
ref missing, ref missing, ref missing, ref missing,
ref missing, ref missing, ref missing, ref missing,
ref missing, ref missing, ref missing);
string ReadValue = string.Empty;
// Activate the document
doc.Activate();
foreach (Word.Range tmpRange in doc.StoryRanges)
{
ReadValue += tmpRange.Text;
}