If you have sensitive data you'd like to keep from prying eyes in a Microsoft Excel file, the easiest way to protect it is with Excel's built-in password tools.

In Word, Excel, or PowerPoint for Windows, open the file you want to protect with a password, then select File and Info. You should see a Protect option at the top of the next list: Click this ...

Whether you’ve forgotten the password or received a protected file from someone else, unlocking an Excel spreadsheet without the password may seem like an insurmountable challenge.