Private Declare Function CopyFile Lib "kernel32" Alias "CopyFileA" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal bFailIfExists As Long) As Long
Sub Macros()
Dim ActiveWorkbook_Path As String
Dim Folder_Old As String, Folder_New As String
Dim OldName As String, NewName As String
Dim i As Long, lLastRow As Long
ActiveWorkbook_Path = ActiveWorkbook.Path
Folder_Old = ActiveWorkbook_Path & "\FolderOld\"
Folder_New = ActiveWorkbook_Path & "\FolderNew\"
lLastRow = Cells(Rows.Count, 1).End(xlUp).Row
For i = 1 To lLastRow
OldName = Folder_Old & Cells(i, 1) & ".txt"
NewName = Folder_New & Cells(i, 2) & ".txt"
CopyFile OldName, NewName, False
Next i
End Sub