'Dim textbox1 As New TextBox With {.Text = "42782,4063949074"}
 
 
Dim dbl As Double, dati As DateTime
 
If Double.TryParse(textbox1.Text, dbl) Then
   dati = DateTime.FromOADate(dbl)  'Double --> Datum/Zeit
   MsgBox("Das Datum ist: " & _
     dati.ToString("dd.MM.yyyy hh:mm:ss")) 'Datum/Zeit --> String
Else
   MsgBox("Es ist kein geeigneter Doublewert gegeben worden")
End If

 Private Sub Button5_Click(sender As Object, e As EventArgs) Handles _
   Button5.Click
        Dim idate As Date
        Dim db As Double
        If Double.TryParse(Trim(TextBox11.Text), db) Then
            ' text is convertible to Double, and value contains the Double 
            ' value now
        End If
        idate = Date.FromOADate(db)
        Debug.Print(idate.ToString)
    End Sub