How can I open an Excel file that Excel "does not recognize this file format"?

Maybe it is Lotus 123?  They had the workpage setup years before MS branded it as theirs. (thus M$ stole it) which is common practice for them.

. Left click and open as a Word Document and take the check mark off that says "always open with this file type" because you do not know if it will work.

.  If it does open, then left click it and save as M$ Excel as another file on the desktop.  Now try opening the new file with Excel and see if it works.

It is a bit of JUGGLING & experimentation to figure out how to work it.

I went to the Microsoft store and downloaded "FreeFileViewer"  Maybe that will help you.?

are you sure it's an Excel file? what is the file extension?

where did it come from? email or did you make it?

ask the person who made it to check. see if they can open it. maybe resend it.

Open in Notepad.  Copy everything.  Paste into a blank excel workbook.  You may have to play with the columns and how the paste is delimited, but that often works.  If it's a pretty complex excel file you can forget about it.  

If you know the source of the file, go back to that program and do a save as excel.

Convert to excel format first (if that is possible).

Change the excel to compatible mode to try.

You can open it in wordpad and try to figure out what kind of file it is.