A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
This issue occurs when the file might be corrupted. You can try manually repairing the file.
1. Open Excel and on the File menu, click Open.
2. In the Open dialog box, select the file you want to open, and click the arrow next to the Open button.
3. Click Open and Repair, and then choose which method you want to use to recover your workbook.
For more information on repairing corrupted files in Excel refer:-
http://office.microsoft.com/en-us/excel/HA010346561033.aspx
If above steps does not work then you can refer the steps given in the below mentioned article:-