John Godley

Enhances the WordPress media library by allowing you to rename the underlying media files. Any change to a media item’s title will result in the media filename also being changed.
See the screenshot for more details of where to rename media files.
Note that all thumbnails will also be renamed. If you are using a caching plugin, such as WP Super Cache, then you will need to clear your cache so that any references are updated. This plugin does not update existing direct links to files (links inside a WordPress gallery will change).

Rename Media

Rename underlying media files from the WordPress media management interface

Milan Dinić

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This plugin enables renaming of media files. It adds a field in media edit form where you can enter new file name. After renaming, it’ll regenerate all intermediate image sizes (if media file is an image) and update all links inside posts.
If you are translator, you can translate it to your language and send translations to plugin’s author. Included translations are for Serbian and German.

Rename Media vs Rename Media Files