To convert xlsx to xls - Microsoft Office Professional 2007 Full Version for PC

You can try XLSX Repair Kit ( - MS Excel XLSX repair tool ) - XLSX file repair software for corrupt Excel workbook. XLSX Repair Kit helps to repair XLSX file content ASAP.

The free Opal-Convert Excel to vCard to Excel might work for you. Opal Convert Excel to vCard to Excel

If the extension of the corrupted file is not xls or xlsx), have you tried renaming it with the xls or xlsx extension and opening with excel? Have you tried opening with Google Docs Spreadsheet?

Two possibilities:

1. You accidentally save it as an HTM or HTML file. It will still open in Excel if so. Open the file in Excel and do a Save As back to an XLS (Excel 97-2003 version file) or XLSX (Excel 2007 - 2013 version file).
2. You associated XLS or XLSX files to be opened with CometBird. If so, right click on the file and choose "Open With," then go to the bottom of the choices and left-click on "Choose default program..." Then choose Excel and you should be all set. Windows will reassociate all your files to automatically open with Excel instead of CometBird.

You don't have to convert the .docX or .xlsX to view in MS Office 2003, just install the "Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint File Formats" and you should be able to open files, created or saved as the MS Office 2007 format.

If you need to edit the files you can too, but you will saved it in the MS Office 2003 formats.

Hope it helps.

.XLSX is an Excel 2007 file from the Office 2007 suite. If you have an older version of Microsoft Office, you can download the "Compatibility Pack" from here:

http://www.microsoft.com/downloads/details.aspx?FamilyId=941B3470-3AE9-4AEE-8F43-C6BB74CD1466&displaylang=en

This will allow you to open 2007 format documents in older versions of Office. If you don't have any version of Office, you can convert it online and have it sent to your e-mail into a file you can open through:

www.zamzar.com

If you don't have any kind of Office Suite, you can get one free at:

www.openoffice.org

This will open Office 2003 files and so you can convert that .xlsx to .xls and open it with that. Hope this is helpful.

Say you got tons of Excel sheets, PowerPoint presentations and Word documents on your computer that were written in Office XP or 2003. How do you convert all these files to the new Office 2007 format. One option is that you open all of them in the associated Office program and manually save them in the newer (docx, xlsx or pptx) format. Or follow these steps and convert all documents in one go.
Step 1: Download Migration Manager kit and extract it into a new folder – say: c:\office.

Step 2: Download and install the Office Pack – this step is required even if you have Microsoft Office 2007 already installed on your computer.
Step 3: Assuming that you extracted the Office Manager files in c:\office directory, go c:\office\tools, open ofc.ini using notepad and add the following line.
fldr=c:\users\labnol\documents
This refers to the folder location that holds your office files. I am pointing this to my Documents folder but it could be different on your machine.
Step 4: Open command prompt and go to c:\office\tools. There you’ll see a utility called ofc.exe – this is the Office File Converter that will convert all old Office files to the new 2007 Office document format in bulk. Run.

Immediately all old Office files in that folder (and sub-folders) will get converted to the new format and are saved in a new folder.
This utility works with Word (doc to docx), Access databases, PowerPoint (ppt to pptx), Visio diagrams, Excel (xls to xlsx) and Microsoft Project files. The conversion may however fail for password protected documents.

Don\'t need to worry even if your excel
files are get corrupt because there are several ways to repair
corrupt excel files. The easiest available solution is to use "Open
and repair" utility of MS excel to repair damaged xlsx or xls files.

use nitropdf. its best software to handle pdf convert. download here