A user protected a single sheet inside Excel .xlsx file and forgot the password. There are multiple ways to unprotect sheets without the password, below is just one of them. Please be aware this will not work if the whole Excel file is protected from opening (encrypted).
- Change the file's extension from .xlsx to .zip.
- Open / extract the file with 7-ZIP (or another similar application).
- Open file xl\worksheets\sheet1.xml in a text editor (or another sheetX, depending on which one is protected).
- Find entry starting <sheetProtection... and remote everything up to and including />.
- Save the changes to the .xml file and .zip files.
- Change extension back to .xlsx
- If you are getting "Unprotected Formula" warnings in the unprotected sheet, select all the affected cells, Right Click > Format Cells > Protection > enable Locked and click OK.
Windows 11 Pro
MS Office 365