Moodle in English

The file is not encryped.

The file name is, however, unhelpful. (It is a SHA1 hash of the file contents, if you are interested.)

To find the right file, you need to restore your database backup, and if you are going to do that, why not restore the entire site onto a spare server, and just download the file you need from that clone.

If you don't want to got that route, then in the restored database, look in the mdl_files table, and you should be able to find a row for the backup file you are after. That will give you the SHA1 hash that is the filename in moodledata/filepool.

Since you appear to be running a version 2.3.x, the backup file might actually still reside on your server.

Has the cron job run and trash been emptied?  Unless you've changed defaults, a file is deleted from the trashdir approximately 4 days from it's placement there.

Logged on as root user and in mooodledata directory:

cd trashdir
ls -lR

Might show something like this:

[root@sos trashdir]# ls -lR
.:
total 4
drwxrwxrwx 3 apache apache 4096 Mar  7 17:42 ab

./ab:
total 4
drwxrwxrwx 2 apache apache 4096 Mar  7 17:42 a3

./ab/a3:
total 2232
-rw-rw-rw- 1 apache apache 2281426 Jan 27 18:50 aba3d3338e892addf8d0127849c587323e31dc82

Then run this:

file -b ab/a3/aba3d3338e892addf8d0127849c587323e31dc82

If the output is:

Zip archive data, at least v2.0 to extract

It's a .mbz backup of a course that can be copied out of the trash and renamed to something.mbz.
One could temporarily copy to web root:
cp ab/a3/aba3d3338e892addf8d0127849c587323e31dc82 /var/www/html/something.mbz

Then, the something.mbz file can be downloaded and through a restore process of your choosing, the something.mbz file can be restored.

You might have quite a few files in the trash, however, to look at. :|

'spirit of sharing', Ken

I'm not sure of .au law, but in the USA the kid (and by extension, his/her parents if it's a minor) would be on the hook for a federal felony and damages under UCC 1340 as well as other laws.

While it might be above your pay grade, track your time and effort on the recovery and suggest the school bill the parents for recovery time.

Stupidity and criminal activity should be made as painful as possible.