The FileExists method checks the existence of a file. It returns –1 if the specified URL exists within a published directory. If the file does not exist, it returns 0.
Tools.FileExists(URL)
FileExists only checks the existence of files published on your site. Therefore, it takes a relative URL rather than an absolute URL.
The following example demonstrates using the FileExists property to create a link if a particular file is present.
<%If Tools.FileExists("ie_animated.gif") then %>
<p> <a href="http://www.microsoft.Com/ie/"><img src="ie_animated.gif"></a>
<% End If %>