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Possible Duplicate:
Excel document can not open

I formatted the hard drive because I had trouble with trojan and saved my document on another hard drive but when I restored my document on the newly formated hard drive I can not open them and I get the following error message:

Excel cannot open the file because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file

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marked as duplicate by Mehper C. Palavuzlar, studiohack Mar 25 '11 at 16:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Can you open the document on the other HDD? – Joe Taylor Mar 2 '11 at 10:19
No I can not. It displays the same message – Paul Mar 2 '11 at 12:23
Can you open the file when copied onto another PC with Excel installed? – Mick Mar 3 '11 at 12:00
duplicate of your Excel document can not open – Mehper C. Palavuzlar Mar 25 '11 at 15:52

Try opening the file in OpenOffice, LibreOffice or Gnumeric

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Are you sure that Excel has been re-installed properly? Windows on its own does not know how to open an xls file. Excel needs to be installed first.

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Excel is well installed and I can see the documents – Paul Mar 2 '11 at 12:33

The error message is probably right: the file is damaged to the point that Excel can't open it properly. Excel has some built-in features to attempt to salvage some part of it: Excel File Repair. If that doesn't work, you could attempt some of the various repair apps out there, but you may spend less time going to an old backup and building from there.

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