How access dynamic added controls from code behind

I've find a solution for problem.Looping through all controls.

public static IEnumerable<Control> GetControls(ControlCollection controlCollection)
{
    foreach (Control control in controlCollection)
    {
        yield return control;

        if (control.Controls == null || control.Controls.Count == 0)
            continue;

        foreach (var sub in GetControls(control.Controls))
        {
            yield return sub;
        }
    }
}

After creating IEnumerable list check for the Control's ID.

    foreach (Control c in ctr__)
    {
        if (c.ClientID == "dropUGrp")
        { 
           //Code goes here
           break;
        }
    }