Update: It is probably wise to try to do a zip repair step on corrupt xlsx files as a first step before trying to invoke other methods.
Microsoft recommends several methods for recovering from Excel corruption. This Excel add-in brings into one toolbar these methods while adding four data recovery methods of its own.
For MS methods for recovering from Excel file corruption, see: http://office.microsoft.com/en-us/excel-help/repairing-corrupted-files-in-excel-HA001034656.aspx or here: http://office.microsoft.com/en-us/excel-help/repairing-a-corrupted-workbook-HA010097017.aspx.
Requires at least Excel 2003 and Windows XP.
Hello, You can also use an other excellent Excel Repair Tool from here repaircorruptexcel.com . It is a very advances software named as Kernel for Excel Recovery that can immediately repair all damaged excel file without any error.