private void TextBox1_Leave(object sender, EventArgs e)
 {
     if (TextBox1.Text.Trim() == "")
     {
         TextBox1.TextBoxEnter();
     }
     else
     {
         TextBox1.Text = TextBox1.Text.ToUpper();
         TextBox1.TextBoxLeave();
     }
 }
 private void TextBox1_KeyDown(object sender, KeyEventArgs e)
 {
     if (TextBox1.Text.Trim() == "" && e.KeyCode == Keys.Enter)
     {
         TextBox1.TextBoxEnter();
         MessageBox.Show("Enter Patient Name");
     }
     else
     {
         TextBox1.TextBoxLeave();
         this.Enter2Tab(e);
     }
 }