If you are a user of Lotus Notes then you must know that NSF file format is used in it for saving data items. But the sad thing is this file is prone to corruption due to reasons like server crash, power outage this file may get corrupt. I think you are also facing the
NSF to PST Converter
Single tool for Lotus Notes to Convert unlimited NSF file to PST and 8+ other conversion formats. This tool supports all versions of IBM Lotus Notes.