Client saves a lot of old messages. Currently the system plays saved messages from oldest to newest. Is there a way to play the messages from newest to oldest?
http://lists.digium.com/pipermail/asterisk-users/2009-May/232193.html
derivitively, perhaps recompile app-directory with
reordered = 1
But as a pragmatist, I would suggest you use human engineering to coerce your “client” to just “not do that shit”, even if he is (my guess) your humilty impaired CEO 
call this like “script 2222/Old”
#!/bin/bash
cd /var/spool/asterisk/default/$1
k=ls *.txt|wc -l
for ((n=0;n< k;n++))
do FIRST=printf %04d $n
LAST=printf %04d $(($k - $n -1))
if [ $FIRST -ge $LAST ]; then break;fi
mv msg$FIRST.txt msgtmp.txt
mv msg$LAST.txt msg$FIRST.txt
mv msgtmp.txt msg$LAST.txt
mv msg$FIRST.wav msgtmp.wav
mv msg$LAST.wav msg$FIRST.wav
mv msgtmp.wav msg$LAST.wav
mv msg$FIRST.WAV msgtmp.WAV
mv msg$LAST.WAV msg$FIRST.WAV
mv msgtmp.WAV msg$LAST.WAV
add sections for other formats used
mv msg$FIRST.gsm msgtmp.gsm
mv msg$LAST.gsm msg$FIRST.gsm
mv msgtmp.gsm msg$LAST.gsm
done
echo “thanks for that dicko!!”
if you want to piss him off, then run it twice 