[ممدوح]

وعليكم السلام ورحمة الله

كود :

Public Class Form1

   Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
       ListBox1.Items.Add(rendomLetters(6))
   End Sub

   Function rendomLetters(length As Integer) As String
       Dim s As String = String.Empty
       Dim arr() As Char = "abcdefghijklmnopqrstuvwxyz".ToCharArray
       Dim r As New Random()
       For i = 1 To length
           s &= arr(r.Next(0, arr.Length))
       Next
       Return s
   End Function

End Class