How to recover after Win7 system closes the taskbar thumbnail?

How can I restore the Win7 system taskbar thumbnail function after various reasons? The following small series will introduce the specific steps for everyone!
1. First type gpedit.msc in the start search box and press Enter to open the local Group Policy Editor.

2. Expand “ User Configuration”-“Administrative Templates”-“Start Menu and Taskbar”

3. In the details window on the right, pull down the scroll bar, Find “close the taskbar thumbnail”item;

4. Double-click to open and change the setting to “not configured” or “disabled”. Then press “OK” to exit;