Sub UpdateDocumentHeaders()
Application.ScreenUpdating = False
Dim strFolder As String, strFile As String, wdDoc As Document
strFolder = GetFolder
If strFolder = "" Then Exit Sub
strFile = Dir(strFolder & "\*.doc", vbNormal)
While strFile <> ""
  Set wdDoc = Documents.Open(FileName:=strFolder & "\" & strFile, AddToRecentFiles:=False, Visible:=False)
  With wdDoc.StoryRanges(wdPrimaryHeaderStory).Find
    .ClearFormatting
    .Text = InputBox("Text to Replace", "Old String")
    .Replacement.Text = InputBox("Replacement Text", "New String")
    .Forward = True
    .Wrap = wdFindContinue
    .Format = False
    .MatchCase = True
    .MatchWholeWord = True
    .MatchWildcards = False
    .MatchSoundsLike = False
    .MatchAllWordForms = False
    .Execute Replace:=wdReplaceAll
  End With
  wdDoc.Close SaveChanges:=True
  strFile = Dir()
Wend
Set wdDoc = Nothing
Application.ScreenUpdating = True
End Sub
 
Function GetFolder() As String
Dim oFolder As Object
GetFolder = ""
Set oFolder = CreateObject("Shell.Application").BrowseForFolder(0, "Choose a folder", 0)
If (Not oFolder Is Nothing) Then GetFolder = oFolder.Items.Item.Path
Set oFolder = Nothing
End Function