WP Media library fails to recognize uploaded files

Problem: The WordPress Media library fails to recognize existing files already uploaded to the blog/wp-content/uploads folder on my server.

Background
* A 16 MB file fails to upload to the WordPress Media library using the multi-file Media and browser uploaders.

* php.ini settings at my server are appropriate:
– ; Maximum allowed size for uploaded files.
upload_max_filesize = 128M
– memory_limit = 64M

* As a possible work-around, I uploaded files directly to the blog/wp-content/uploads using FTP. However, the WordPress Media library fails to see those uploaded files.

Request: Please create a way to force the WordPress Media library to recognize files already uploaded to blog/wp-content/uploads on users servers.