What Is an .XLK File?
Excel left an .xlk file beside your spreadsheet. It is Excel's backup copy. Here is how to open it and recover your data.
What an XLK file is
An .xlk file is an Excel backup workbook. When you enable Always create backup (in the Save As → Tools → General Options dialog), Excel keeps the previous saved version as Backup of <name>.xlk in the same folder. It is essentially your spreadsheet one save behind.
How to open it
Open Excel, choose File → Open, and either set the file type to All Files or just rename a copy of the .xlk to .xls or .xlsx and open it. Then Save As a normal workbook.
Is it safe to delete?
Yes, when your main workbook is healthy. Deleting the .xlk removes only the spare copy; the working spreadsheet is not affected.
FAQ
How do I open an .xlk file?
In Excel use File → Open with type set to All Files, or rename a copy to .xls/.xlsx and open it, then Save As.
Is an .xlk the same as my spreadsheet?
It is the previous saved version of it — your data one save behind.
Can I delete .xlk files?
Yes, if the original workbook is fine. It is only a backup.