Option Explicit

Private Function UstalZakres() As Integer
Dim i As Integer

i = 1

Do While (Worksheets("Arkusz1").Cells(i, 1).Value <> "")
    i = i + 1
Loop

UstalZakres = i - 1

End Function

Public Sub Wypelnij()

Dim lista As Range
Dim i As Integer
Dim komorka As Object

Set lista = Me.Range("A1:A" & UstalZakres)
lista.Sort Key1:=lista.Columns("A")

ListBox.Clear

For Each komorka In lista
    ListBox.AddItem (komorka.Value)
Next komorka

Set lista = Nothing

End Sub