I have spent two hours working on an Excel file which was sent to me via email. I have saved the file on to a memory stick saving it as "copy of" but now when I try to open the file the following message appears "Excel cannot open the file "File name....." 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"

How do I do that or how can I access the file?

I am only a basic user of Excel files so do not understand all the technical terms etc.

Can anyone help me as I need the information on the file by tomorrow.

Thanks