Try the following code
Sub Merge()
Dim ws As Worksheet
'Application.ScreenUpdating = False
'loop thrue all sheet
'For Each Sheet In Sheets
Sheets("Merge").Select
ActiveSheet.UsedRange.Offset(0).Clear
For Each ws In ActiveWorkbook.Worksheets
'skip active sheet
If ws.Name <> ActiveSheet.Name Then
If ws.Name = "Files" Then Exit For
'If Sheet.Name <> ActiveSheet.Name Then
'Sheet.Range("A1:C10").Copy
ws.UsedRange.Offset.Copy
'find last empty cell in column A
Range("B65536").End(xlUp).Offset(1, -1).Select
'paste the copied data
Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False
Selection.PasteSpecial Paste:=xlFormats, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False
'ActiveSheet.Paste
End If
Next
'Application.ScreenUpdating = True
'100
Range("a1").Select
Application.CutCopyMode = False
Cells.Select
'Cells.EntireColumn.AutoFit
Range("A1").Select
Sheets("Headings").Select
End Sub