How to recover deleted file from LUKS encrypted hard disk

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http://www.linuxquestions.org – By mistake i deleted my lotus notes folder which have my last 7 years mail archive . My hard disk is LUKS encrypted . I tried to restore the data using photorec . it's restored the file *.gpg (I confirmed this gpg file as my required nsf file with comparing the size of the file) but it's says the file PGP/MIME encrypted and I couldn't open that file using my lotus notes after renaming it to *.nsf. Do we have any way to decrypt this single file? or any way to restore the file from LUKS encrypted harddisk .. I read in some thread as Use "dd/dd rescue" command first then use photor (HowTos)