How to recover my lost files in my nokia e6 while decrypting it back to my sd card?

I was encrypting my SD card file on my Nokia E5 phone (Control Panel > Data manager > Encryption) but it was making my phone slower and ended up hanging. I restarted the phone with no other option and when I check the SD card, all the files had disappeared. Please suggest me the possible solutions. I really need those files.

via Forums de téléphone cellulaire (en français) http://cellphoneforums.net/fr/nokia/t362470-how-to-recover-my-lost-files-in-my-nokia-e6-while-decrypting-it-back-to-my-sd-card.html