Settings - Server - Library - Empty trash automatically after every scan = Disable
If this checkbox was ‘checked’, then you must https://support.plex.tv/articles/202485658-restore-a-database-backed-up-via-scheduled-tasks/ from before the crash.
If it was already disabled, you can proceed to install:
This plugin allows you to scan a library and check for any missing files. It then displays a list of missing files or lets you know if none are missing.
or
ExportTools
Which gives you a list of every media item in a certain library. Optionally with the file path. (you need to configure the detail ‘level’).
You can then open the resulting CSV or XLS file with a spreadsheet app and sort by path.
how to install a plugin:
https://support.plex.tv/articles/201187656-how-do-i-manually-install-a-plugin/
