Welcome to the Forum robottom although this is not really a support site for MS Office.
 
Did you make a copy before you updated it?
Do you have Backups?
What Version of Excel was the File before you said save it as an 2013 Version File?
Did you have any add-ons in the older version?
Have you tried to repair the file in Excel?
Is the this an XLSM or XLSB or standard XLSX File?

If you copy the file and rename it to test.zip can you open the zip file?
You should see this:
(Folders)
_rels
docProps
xl
(File)
[Content_Types].xml
in this file you should see: 

<?xml version="1.0" encoding="UTF-8" standalone="true"?>
<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"><Default ContentType="application/vnd.openxmlformats-package.relationships+xml" Extension="rels"/><Default ContentType="application/xml" Extension="xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml" PartName="/xl/workbook.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml" PartName="/xl/worksheets/sheet1.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml" PartName="/xl/worksheets/sheet2.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml" PartName="/xl/worksheets/sheet3.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.theme+xml" PartName="/xl/theme/theme1.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.connections+xml" PartName="/xl/connections.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml" PartName="/xl/styles.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml" PartName="/xl/sharedStrings.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.queryTable+xml" PartName="/xl/queryTables/queryTable1.xml"/><Override ContentType="application/vnd.openxmlformats-package.core-properties+xml" PartName="/docProps/core.xml"/><Override ContentType="application/vnd.openxmlformats-officedocument.extended-properties+xml" PartName="/docProps/app.xml"/></Types>
 
 
If not then the file is gone and you are mostly out of luck getting any data back.
 
If you copy the file and rename it to test.xls see if you can open it this way!

robottom
A few hours ago, I updated my working file in Excel 2013 all changes are saved. I decided to look at what I did. When I open a file the program generated an error - Excel found no readable content. I tried to open a file on another computer, nothing happened.
 
What should I do, tell me whether you can open the file?

Try to open excel file in other version of MS Excel 2007 or 2003, in case file isn't opened, then you may search backup copies of file in excel folders. Finally there is a solution , which is used in complex cases