Corrupted .NSF file is overwritten

Please help. I found my Lotus .NSF file corrupted as it was having 0 Kb in size. Due to improper resolution, it was overwritten to fix the archiving issue. Now that the file size has become 22MB which is default file size for any .NSF file. Now, please help me, I have lost all my mails and when I try to recover, it recovers only from the overwritten file and not from the original corrupted file. Is there any good software to revert the overwritten and recover the corrupted file?