thank you my friend,
that worked
now to do a single file with lots of replacements i only added the file name below
Sub Search_Replace_TextFile()
Const ForReading = 1
Const ForWriting = 2
Dim objFSO As Object
Dim objFile As Object
Dim fName As String
Dim i As Long, LR As Long
Dim strText As String, strNewText As String
LR = ThisWorkbook.ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
Set objFSO = CreateObject("Scripting.FileSystemObject")
For i = 2 To LR
fName = "C:\Users\DJ\Desktop\a.txt" ' <<< Single Text file
Set objFile = objFSO.OpenTextFile(fName, ForReading)
strText = objFile.ReadAll
objFile.Close
'Case insensitive
strNewText = Replace(strText, Range("C" & i), Range("D" & i), Compare:=vbTextCompare)
'Case sensitive
'strNewText = Replace(strText, Range("C" & i), Range("D" & i), Compare:=vbBinaryCompare)
Set objFile = objFSO.OpenTextFile(fName, ForWriting)
objFile.WriteLine strNewText
objFile.Close
Set objFile = Nothing
Nexti:
Next i
Set objFSO = Nothing
End Sub
I was trying to lots of replacements in my text file, one by one is very tedious 
But this will help me do it one press
cheers and good week!