Plex plugin to search a library and list any missing files.
Click on the "Download ZIP" button to the right of the main screen
See the following for the plugin location: https://plexapp.zendesk.com/hc/en-us/articles/201106098-How-do-I-find-the-Plug-Ins-folder
Extract zip, and copy it to your Plex Server plugins folder so all the files from this download ends up in a directory named "FindMissing.bundle"
Then restart your Plex Server, and look under Channels (Under Applications if running from a Samsung device), where you should be able to find a new channel (Might have to wait some time before it shows, if running on a slow PMS server, aka an ARM based one)
Note that it's strongly recommended, that you run an optimize of your database before running this plug-in, in order to make it faster.
To optimize, on the main page of the web-manager, select @ the upper right the button named "More"