We are unable to address this issue because it is related to third-party software. Contact Microsoft for assistance. If you cannot find the document at all in Excel, you will have to run the export again. Please be sure to note the file path and document name so you can find it in Microsoft.
Alternative solution:

Export from the Query or Export module again and note the default path name. Unless you changed it when originally exporting, this is where you should be able to find the spreadsheet.
OR
If using a Mail Merge to create your export, print the control report as it includes the name/path to the exported file.