I find child control using VisualTreeHelper in WPF. VisualTreeHelper provides all children in form nodes in a visual tree.

Visual tree is used for rendering, routing and locating resource.

Namespace of VisualTreeHelper is System.Windows.Media

Here, below is the example.

Adding namespaces:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

Method to find all children control

private List<Control> AllChildren(DependencyObject parent)
		{
			var list = new List<Control> { };
			for (int count = 0; count < VisualTreeHelper.GetChildrenCount(parent); count++)
			{
				var child = VisualTreeHelper.GetChild(parent, count);
				if (child is Control)
				{
					list.Add(child as Control);
				}
				list.AddRange(AllChildren(child));
			}
			return list;
		}

You have to call this method like this:

List<Control> children=AllChildren(ItemsControl1);   

ItemsControl1 is the name of ItemsControl. You can pass any WPF control to finds its all children control.

Hope this code will help you. Thanks