how can i reference the file name so that whenever i run this macro in other
file i dont have to go to and change the Worrkbook name and worksheet name. i
want it to recognize it itself because i am going to be usign the macro on
multipe excel file.

here is the code
Public Sub Tester()
Dim WB As Workbook
Dim SH As Worksheet
Dim rng As Range
Dim rCell As Range

Set WB = Workbooks("*.xls")
Set SH = WB.Sheets("VT Masterlist") '
Set rng = SH.Range("A:A")


For Each rCell In rng.Cells
With rCell
ipos = InStr(rCell.Value, ".")
If ipos 0 Then
rCell.Value = Left(rCell.Value, ipos - 1)
End If
End With

Next rCell

End Sub