Problem reopening a form in C#.NET

I think you need to look at why this data is copied when you hide and then show the form again.
Try moving that logic out of its current position into some other place.

Try this,

public partial class Expedientes : UserControl
    {
    FormX AddNewForm = null;
   private void button1_Click(object sender, EventArgs e)
   {
    AddNewForm = new FormX();
    AddNewForm.button1.Click+= new EventHandler(XEvent);
    AddNewForm.Show();
   }
  private void button2_Click(object sender, EventArgs e)
   {
     if (AddNewForm!=null)
         AddNewForm.Close();
   }
  private void XEvent(object sender, EventArgs e)
   {
    this.textBox1.Text=AddNewForm.textBox1.Text;
   }
}

Mark it as answer if it is helpful.

As per the Venkatesh Mookkan answer, it's fine but check it on a condition.
open your form and click on button1 it will open another form, as many as time you will click(without closing the form) it will open a new form, which is accually not a good thing. so just check a condition in button1_click()


if(AddNewForm==null)
AddNewForm = new FormX();
AddNewForm.button1.Click+= new EventHandler(XEvent);
AddNewForm.Show();

if (AddNewForm != null)
{
   AddNewForm = new FormX();
   AddNewForm.button1.Click+= new EventHandler(XEvent);
   AddNewForm.Show();
}
else
{
   AddNewForm.button1.Click+= new EventHandler(XEvent);
   AddNewForm.Show();
}

building button1.Click like this will help. if u prevent multiple instances u need this. Because a fresh form is null but a closed one is not. so if it is not null it means a closed one and needs to be recreated. otherwise null one means a fresh one and showing will work fine.