Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
   System.EventArgs) Handles Button1.Click
        If TextBox1.Text = "" Or TextBox2.Text = "" Or TextBox3.Text = "" Or _
        TextBox4.Text = "" Then
            Button1.Enabled = False
        Else
            Button1.Enabled = True
 
        End If
    End Sub
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Button1.Enabled = False
    End Sub