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I've seen third-party applications save files with &quot;.xls&quot; extensions that are, in reality, comma-separated values (csv) files. &nbsp;Change the extension to what you think it's supposed to be and try opening it again.<br />
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Show the entire filename here and that may help us resolve this. &nbsp;Make sure it includes the file extension (letters after the period).<br />
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-Glenn
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I've seen third-party applications save files with ".xls" extensions that are, in reality, comma-separated values (csv) files.  Change the extension to what you think it's supposed to be and try opening it again.

Show the entire filename here and that may help us resolve this.  Make sure it includes the file extension (letters after the period).

-Glenn

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Make sure that the extensions are actually linked to the appropriate application:<br />
Control Panel&gt;Default Programs&gt;Associate a file type or protocol with a a specific program
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Make sure that the extensions are actually linked to the appropriate application:
Control Panel>Default Programs>Associate a file type or protocol with a a specific program

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A file is in a different file format than its extension indicates<br />
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The file that you are trying to open in Microsoft Office 2010, 2013has a file name extension that does not match the actual file format of the file. This happen overnight. Please advise.
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A file is in a different file format than its extension indicates

The file that you are trying to open in Microsoft Office 2010, 2013has a file name extension that does not match the actual file format of the file. This happen overnight. Please advise.

the file you are trying to open is in a different format xls for EXCEL and WORDS

Microsoft Office is an integrated suite of applications that includes Outlook, Word, Excel, Access, PowerPoint, Visio and InfoPath, along with a number of tools to assist in making the individual components work together. Coding within and between the projects is done in Visual Basic for Applications, known as VBA.

Microsoft Office

Microsoft Excel topics include formulas, formatting, VBA macros and user-defined functions, and everything else related to the spreadsheet user interface, including error messages.

Microsoft Excel

Microsoft Word is a commercial document editing program that is part of the Microsoft Office suite. It features numerous text-editing tools for creating richly formatted documents, along with tools for the use of macros in Word documents. Word's native file formats are denoted either by a .doc or .docx file extension. Plugins permitting the Windows versions of Word to read and write formats it does not natively support, such as the OpenDocument format (ODF) are available. Word can import and display images in common bitmap formats such as JPG and GIF. It can also be used to create and display simple line-art.