Some sites may have a customized "files" view from which site managers/content managers can audit the files that have been uploaded in conjunction with the content entry process on the site.  This view can be used to audit for files that are no longer used, as well as for files can be optimized (resaved in a more web-friendly format and for faster loading/downloading).  [This "files" view feature requires both Drupal's Filebrowser and File Entity modules to be installed and configured.]

If your site has this feature enabled, you can access and use the "files" view as follows.

1. Navigate to Content > Files.

2. Use the filters across the top of the view to narrow down your selection.

3. Click the link in the "Used in" column to see a list of nodes where the file is embedded/used.  

4. Click the title of the node to navigate to it's detail page and then be able to edit the node/change out the file asset.