Codenstuff.com

'ontop of private sub add this:

Private Const APP_NAME As String = "SaveRestoreListBox"
    Private Const SECTION_NAME As String = "Items"

'then under private sub:

Dim i As Integer = 0
        Do
            Dim new_value As String = GetSetting(APP_NAME, _
                SECTION_NAME, "Item" & i.ToString())
            If new_value.Length = 0 Then Exit Do

            ListBox1.Items.Add(new_value)
            
            i += 1
        Loop

For i As Integer = 0 To ListBox1.Items.Count - 1
            SaveSetting(APP_NAME, SECTION_NAME, "Item" & _
                i.ToString(), ListBox1.Items(i).ToString())
            SaveSetting(APP_NAME, SECTION_NAME, "Item" & _
                i.ToString(), ListBox2.Items(i).ToString())
            SaveSetting(APP_NAME, SECTION_NAME, "Item" & _
                i.ToString(), ListBox3.Items(i).ToString())
        Next i

    Dim lines As List(Of String)

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        ListBox1.Items.Clear()
        Dim lines_a As String() = File.ReadAllLines("lines.txt")
        lines = New List(Of String)(lines_a)

        For i As Integer = 0 To lines.Count - 1
            ListBox1.Items.Add(lines(i))
        Next
    End Sub

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        lines.Add("new item")
        File.WriteAllLines("lines.txt", lines.ToArray())
        Form1_Load(Nothing, Nothing)
    End Sub

    Private Sub btnRemove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRemove.Click
        lines.RemoveAt(ListBox1.SelectedIndex)
        File.WriteAllLines("lines.txt", lines.ToArray())
        Form1_Load(Nothing, Nothing)
    End Sub