Excel users often lock their files to protect data and calculations from unauthorised changes or accidental tampering. If you've forgotten your password, you can use an Excel macro that implements a simple brute force algorithm to unlock your worksheets or workbooks. Another method is to "unlock" the sheet by making an unprotected copy of its contents. This method may not prove to be effective, however, if the entire workbook itself is password-protected.
Launch Excel. Open the workbook containing the sheet that you'd like to unlock.
Count the number of columns in your worksheet or take note of the header of the rightmost column. Be sure to take hidden formulas and columns into consideration.
Enter the following range into the Name Box (the text field located to the left of your Formula Bar).
Replace "B" with the header of the rightmost column. For example, if the worksheet has 26 columns of data, it's rightmost header would be "Z."
Click the "Copy" button under the "Home" tab.
Create a new sheet by holding down "Shift" and pressing "F11."
Select cell "A1" on the new sheet. Click the "Paste" button under the Home tab. You now have an unprotected copy of the protected worksheet.
Download the "allinternalpasswords.xls" workbook (see Resources for a link). This workbook contains the macro that you need for unlocking protected workbooks and sheets. Open it by double-clicking on its icon.
Open the workbook that you'd like to unlock.
Go to the "Add-Ins" tab. Click the "Remove Passwords" button. If it's not there, make sure that you have "allinternalpasswords.xls" open.
Click "OK" to start unlocking your workbook and worksheets. This may take from two to five minutes, depending on the length of the password, the size of the file and the version of Excel you are using.
Unlock sheets and workbooks only if they belong to you or if you are authorised to view them. It's often considered offensive and unethical to unlock another person's protected file without permission. It's good idea to scan files that you download with a reliable antivirus or antispyware program.