In Vista, restoring the accidentally deleted "Show Desktop" icon is not complicated at all: Vista itself keeps a backup of the "Show Desktop" icon and shortcut. All we need to do is copy it to the user directory.
Here are the steps:
Open Explorer.
First, you need to enable Explorer to show system and hidden files. The specific method is as follows: click on "Organize", then "Folder and Search Options". In the pop-up window, select the "View" tab, uncheck "Hide protected operating system files" and adjust the "Hidden files and folders" setting to "Show hidden files, folders, and drives".