[Adrees]

في الحدث Form1_Load اكتب الكود التالي

كود :

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If txtCRN.Text = "" Then
            TextBox1.Enabled = False
            TextBox2.Enabled = False
            TextBox3.Enabled = False
        End If

    End Sub

وفي الحدث txtCRN_TextChanged اكتب هذا الكود

كود :

Private Sub txtCRN_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtCRN.TextChanged
        If txtCRN.Text = "" Then
            TextBox1.Enabled = False
            TextBox2.Enabled = False
            TextBox3.Enabled = False

        Else
            TextBox1.Enabled = True
            TextBox2.Enabled = True
            TextBox3.Enabled = True

        End If

    End Sub