This article shows how to find a Control when using Master Pages in Asp.NET 2.0.

Sometimes is very common the need to find a control when using MasterPages,
or when you are trying to find a control inside some component.

This code below searches for a control in the page hierarchy of controls.

protected void doSomething()
{
    Label label = (Label) FindControlRecursive(this.Master, "FieldNameID");
    label.Text = texto;
}

public Control FindControlRecursive(Control Root, string Id)
{
    if (Root.ID == Id)
        return Root;

    foreach (Control Ctl in Root.Controls)
    {
        Control FoundCtl = FindControlRecursive(Ctl, Id);
        
        if (FoundCtl != null)
            return FoundCtl;
    }
    return null;
}