Ubuntu deleted files from guest account desktop

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http://askubuntu.com – I have Ubuntu 12.10 and was using guest account. I downloaded some files on desktop and shutdown my m/c after use. Now today when I logged in to guest account to copy those files but those surprisingly those files were gone and desktop was clear. I guess ubuntu deletes all files from guest account on shutdown. Can you please guide me to recover those lost files. Thanks (HowTos)