I am assuming you mean chat logs
Are you using Microsoft's own Caht log system or Messenger Plus's Chat log system?
If Plus Chat Logs....
Are your files encrypted chat logs or unencrypted html files?
Have you tried using Messenger Plus' built in chat log viewer?
Have you tried a system restore?
Have you looked in the recycle bin or used Piriform's Recuva application (if you've deleted any files)?
Are you sure the chat log feature is working and turned on for your contacts?
Hope you find your chat logs/get them working
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