Try This
private void mnuYourForm(object sender, EventArgs e)
{
if (IsFormAlreadyLoaded("YourFormName") == true)
{
return;
}
}
Call This routine Before you open your form as shown above
private bool IsFormAlreadyLoaded(string formToLoadName)
{
foreach (Form frmChild in this.MdiChildren)
{
if (frmChild.Name == formToLoadName)
{ frmChild.Activate(); return true; }
}
return false;
}
This Will Definitely work