Microsoft excel is the most popular office form processing software.People always have many important form files need to processed by MS Excel.
So becareful to format hard drive,if not,you will lose important data.But do not worry about it,you can recover your excel file with data recovery software [http://www.luckyrecovery.com].
Microsoft Excel (full name Microsoft Office Excel) is a spreadsheet-application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables and a macro programming language called VBA (Visual Basic for Applications). It has been the most widely used spreadsheet application available for these platforms since version 5 in 1993[citation needed]. Excel is part of Microsoft Office.
Excel was the first spreadsheet that allowed the user to define the appearance of spreadsheets (fonts, character attributes and cell appearance).
When Microsoft first bundled Microsoft Word and Microsoft PowerPoint into Microsoft Office in 1993, those applications had their GUIs redesigned for consistency with Excel,the killer app on the PC at the time.
For Windows OS,MS Excel have many versions:
1987 Excel 2.0,1990 Excel 3.0,1992 Excel 4.0,1993 Excel 5.0,1995 Excel for Windows 95,1997 Excel 97,1999 Excel 2000.
2001 Excel 2002 (version 10) included in Office XP.
2003 Excel 2003 (version 11) included in Office 2003.
2007 Excel 2007 (version 12) included in Office 2007.
Microsoft Excel up until 2007 version used a proprietary binary file format called Binary Interchange File Format (BIFF) as its primary format.
Excel 2007 uses Office Open XML as its primary file format, an XML-based format that followed after a previous XML-based format called "XML Spreadsheet" ("XMLSS"), first introduced in Excel 2002. The latter format is not able to encode VBA macros.
Once there is any problem that may cause Windows reinstallation, people have to format system drive, no matter system is crashed or not (some computer users always reinstall Windows to keep their system clean and safe). After format, they will immediately remember that their excel files are still in "My Documents", and they are really vital for work or life.

At this special moment, all they are thinking is how to get excel files back.