Could not reference the correct DLL for MS word 2013

Unable to cast COM object of type 'Microsoft.Office.Interop.Word.ApplicationClass' to interface type 'Microsoft.Office.Interop.Word._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00020970-0000-0000-C000-000000000046}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).

using Microsoft.Office.Interop.Word;
using Word = Microsoft.Office.Interop.Word;
....
        private void button1_Click_1(object sender, EventArgs e)
        {
            Object oMissing = System.Reflection.Missing.Value;
            Object oFalse = false;
            Object name;

            Microsoft.Office.Interop.Word.Application wrdApp = 
                      new Microsoft.Office.Interop.Word.Application();
            Microsoft.Office.Interop.Word.Document wrdDoc = 
                      new Microsoft.Office.Interop.Word.Document();
            //wrdApp.Visible = true; //MS Word did not appear 
            Object ss = "KeleshaSanad.Docx";
            wrdDoc = wrdApp.Documents.Open(ref ss, ref oMissing,
            ref oMissing, ref oMissing, ref oMissing, ref oMissing,
            ref oMissing, ref oMissing, ref oMissing, ref oMissing,
            ref oMissing, ref oMissing, ref oMissing, ref oMissing,
            ref oMissing, ref oMissing);
        }