For Each item As Object In ListBox1.Items
If CType(item, String) = TextBox1.Text Then
Dim index As Integer = ListBox1.Items.IndexOf(CType(item, String))
MessageBox.Show(String.Format("Value {0} has been found at index position {1}", TextBox1.Text, index))
End If
Next
This example shows you how to find a single value and its index within a list box, you could easily modify it to make a collection of the index results.