Microsoft Excel has several features designed to help you recover unsaved versions of files and prevent data loss.

XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save workbooks, but can also use the XLS format.

When you create and save a spreadsheet using Microsoft Works, the file is saved as an XLR file. This file type is specific to Microsoft Works, and many versions of Microsoft Excel cannot understand ...