Things aren’t quite as hopeless if you want to unprotect a single Excel worksheet but no longer know the password. There is actually a trick for that. However, it involves file manipulation, and there’s no guarantee it will work with all current and future versions of Excel. Of course, we assume that you will try this only if you are authorized to do so.
Step 1: Before performing any of the steps below, make a copy of the relevant Excel file. Perform the following steps within the copied version, because if you make a mistake while modifying the file, you still have the unmodified original available and can start over.
Step 2: Open the copy of the file with 7-Zip. The 7-Zip program comes pre-installed in Windows 10, so all you need to do is right-click on the file and select “Open” from the “7-Zip” menu. If 7-Zip is not installed on your system, download it online – it’s free.