Dim i As Integer = 0
 
    Private Sub PictureBox1_Click(sender As System.Object, e As _
      System.EventArgs) _
            Handles PictureBox1.Click
        If i = 0 Then
            PictureBox1.Load("gedrückt")
            i = 1
        Else
            PictureBox1.Load("ungedrückt")
            i = 0
        End If
    End Sub
 
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) _
      Handles MyBase.Load
        PictureBox1.Load("ungedrückt")
    End Sub