Hi Bluegum.
First, are you sure it’s gone? You would need to delete and then empty the trash in the Manager to get rid of it. If you said to delete it but haven’t emptied the trash, it can be undeleted.
I’m assuming that you mean the unauthorized page from the MODx sample blog site that gets installed automatically. If it is really gone, don’t panic. To recreate it, just create a new document, paste in the code below, and the go to Tools | Configuration and put the unauthorized page ID of the new page in the unauthorized page field on the General tab.
Title: [*loginName*]
Long Title: Login to Enable to Comments
Alias: login
Menu Title: [*loginName*]
<p>In order to comment on blog entries, you must be a registered user of [(site_name)]. If you haven't already registered, you can <a href="[~5~]">request an account</a>.</p>
<div>[!WebLogin? &tpl=`FormLogin` &loginhomeid=`2`!] </div>
Be sure to turn the Rich Text editor off before pasting the code.