bu fonksiyon ile sayfa isminde kayıtlı olan son id numarasını buluruz

Function findLastCount(sheetName As String, Optional ayrac As String = "_") As Integer
    Dim lastCount As Integer
    Dim Ws As Worksheet
    Dim lastUnderlineIndex As Integer
   
    For Each Ws In ActiveWorkbook.Worksheets
        If (InStr(Ws.Name, sheetName) > 0) Then
            lastUnderlineIndex = InStrRev(Ws.Name, ayrac)
            lastCount = CInt(Mid(Ws.Name, lastUnderlineIndex + 1, Len(Ws.Name) - lastUnderlineIndex))
        End If
    Next Ws
   
    findLastCount = lastCount

End Function