Dim t As Hyperlink
For Each t In ThisDocument.Hyperlinks
  t.Address = Replace(t.Address, "google.com", "yandex.ru")
Next

Dim HL As Hyperlink, DC As Document, FileName As String, Path As String, i As Integer
Path = "c:\"

FileName = Dir(Path + "*.doc*")
Do Until FileName = ""
    Set DC = Documents.Open(Path + FileName)
    For Each HL In DC.Hyperlinks
      HL.Address = Replace(HL.Address, "google.com", "yandex.ru")
    Next
    DC.Close True
    Set DC = Nothing
    i = i + 1
    FileName = Dir
Loop
MsgBox "Обработано файлов: " + CStr(i)