Hi,
Try this:
Create a class like above:

class ListItem
{
public object Id = null;
public string Text = null;

public ListItem(object id, string text)
{
this.Id = id;
this.Text = text;
}

public override string ToString()
{
return this.Text;
}
}

When you added the line to listbox you will use

this.listBox1.Items.Add(new ListItem(1,
"Name:Jhon\tE-mail:mail@gmail.com\tPhone:+40298123456\tSex:Male"));

Ehen you get the selected line in the listbox, you will use

id = ((ListItem) this.listBox1.SelectedItem).Id;

Hope this is help you.
Mihaly

Did you try System.Environment.Newline instead of \n? Technically a new
line is denoted by \r\n on Windows Hosts, not just \n.

Chris.