using a dialog box to select the file for consolidation

Set Wbk = Workbooks.Open("D:\data files of Roshan\Global_HEADCOUNT.xls")       '<-------Set Path of the global headcount file >
       Worksheets("GLOBAL_HEADCOUNT").Select                                          '<-------Set the sheet name of the head count file>
       Mastcol = Cells(1, Columns.count).End(xlToLeft).Column
       j = Cells(Rows.count, 1).End(xlUp).Row
       Set mastRng = Range(Cells(1, 1), Cells(1, Mastcol))
       b = mastRng
    
    For k = 1 To lastCol
        For n = 1 To Mastcol
            If UCase(a(3, k)) = UCase(b(1, n)) Then
            Windows("Global_HEADCOUNT").Activate     '<-----Set the name of the global headcount file>
                Worksheets("GLOBAL_HEADCOUNT").Range(Cells(2, n), Cells(j, n)).Copy     '<------Set the name of the sheet in the global headcount file>
                Windows("RMG Dashboard.xlsm").Activate    '<------Set name of the dashboard file>
                Worksheets("Dashboard").Select            '<------Set name of the sheet in the dashboard file>
                Cells(i + 1, k).PasteSpecial Paste:=xlPasteAll, Operation:=xlNone, SkipBlanks:=False, Transpose:=False
                Exit For
            End If
        Next
    Next
    Call Wbk.Close(False)

'The folder containing the files to be recap'd
Set fd = Application.FileDialog(msoFileDialogFilePicker)
fd.InitialFileName = "G:\Work\" '<----- Change this to where the files are stored.
fd.InitialView = msoFileDialogViewList
'allow multiple file selection
fd.AllowMultiSelect = True
fd.Filters.Add "Excel Files", "*.xls*"
filechosen = fd.Show
'Create a workbook for the recap report
Set Master = ThisWorkbook
If filechosen = -1 Then

Dim f As Object, fso As Object, flder As Object
Dim myfile As String
Dim wb As Workbook, ws As Worksheet
Set wb = ActiveWorkbook ' this variable lets us go back to our original workbook
Set ws = ActiveSheet ' this variable lets us go back to our original sheet
Set fso = CreateObject("Scripting.FileSystemObject")
With Application.FileDialog(msoFileDialogFilePicker)
    .Show
    If .SelectedItems.Count = 0 Then
        MsgBox "Cancel Selected"
        End
    End If
    myfile = .SelectedItems(1)
End With
Dim wbk As Workbook ' use this variable to reference the workbook we're opening
Dim ghws As Worksheet ' this variable should reference the new sheet that gets opened
Set wbk = Workbooks.Open(myfile)
Set ghws = ActiveSheet




ghws.Select
Mastcol = Cells(1, Columns.Count).End(xlToLeft).Column
j = Cells(Rows.Count, 1).End(xlUp).Row
Set mastRng = Range(Cells(1, 1), Cells(1, Mastcol))
b = mastRng




For k = 1 To lastCol
    For n = 1 To Mastcol
        If UCase(a(3, k)) = UCase(b(1, n)) Then
        wbk.Activate
            ghws.Range(Cells(2, n), Cells(j, n)).Copy
            wbk.Activate
            ws.Select
            Cells(i + 1, k).PasteSpecial Paste:=xlPasteAll, Operation:=xlNone, SkipBlanks:=False, Transpose:=False
            Exit For
        End If
    Next
Next
Call wbk.Close(False)