You must to know GUID of the object to extract.

Example:

$entity_guid = (int) get_input('guid');

$entity = get_entity($entity_guid);

$entity_name = $entity->getDisplayName();

Read also http://learn.elgg.org/en/1.11/guides/views.html#listing-entities

I got the guid, passed it in, and got the same error that the entity does not exist.

What you do it? Post all code, please.

What version of Elgg? You may need to upgrade to get the getDisplayName method.

Or try using getTitle() instead.

If it's a blog and you want the title then do:

$entity = get_entity($entity_guid);
$entity_title = $entity->title;
echo $entity_title;

This also works for pages, discussions, groups, etc.

Are you sure the object got created in the first place? How did you create it? How do you know the GUID you have is the correct one?