if (e.Key == Key.Return && (e.Key == Key.LeftCtrl || e.Key == Key.RightCtrl))
 {
   //Do Something
 }

void SpecialKeyHandler(object sender, KeyEventArgs e)
{
    // Ctrl + N
    if ((Keyboard.Modifiers == ModifierKeys.Control) && (e.Key == Key.N))
    {
        MessageBox.Show("New");
    }

    // Ctrl + O
    if ((Keyboard.Modifiers == ModifierKeys.Control) && (e.Key == Key.O))
    {
        MessageBox.Show("Open");
    }

    // Ctrl + S
    if ((Keyboard.Modifiers == ModifierKeys.Control) && (e.Key == Key.S))
    {
        MessageBox.Show("Save");
    }

    // Ctrl + Alt + I
    if ((Keyboard.Modifiers == (ModifierKeys.Alt | ModifierKeys.Control)) && (e.Key == Key.I))
    {
        MessageBox.Show("Ctrl + Alt + I");
    }
}

if (e.Modifiers == Keys.Control && e.KeyCode == Keys.Enter)

if (e.KeyChar == 10)
            {
             ///Code
            }

if ((Char)e.KeyChar == 'n')
            {
             ///Code
            }

if ((Keyboard.Modifiers == ModifierKeys.Control) && (e.Key == Key.Enter))
        {
            Button_Click_Save(sender, e);
        }