When Ever You Want To Do Any Events Like Hide,Close,Show Of A Form From Another Form You Can Use Following Code.
When Ever Dispose a Object In A Form From Another Form Make Sure All The Child Class Objects Relevant To That Object Are Closed.
for (int index = Application.OpenForms.Count - 1; index >= 0; index--)
{
if (Application.OpenForms[index].Name == "Your Form Name")
{
Application.OpenForms[index].Close();//To Close
}
else if (Application.OpenForms[index].Name == "Your Form Name")
{
Application.OpenForms[index].Hide();//To Hide
}
else if (Application.OpenForms[index].Name == "Your Form Name")
{
Application.OpenForms[index].Show();//To Show
}
}