Four separate situations can cause Excel 2013 to open a file as read-only or otherwise prevent you from editing cells or saving changes, and each has its own solution. For files marked "read-only recommended," create a new copy of the file without this option. If the file has the read-only flag in Windows, disable it in the file's properties. If a file opens in Protected View, unblock it or disable Protected View entirely. Finally, for workbooks with protected sheets, turn off protection in Excel to make changes.
Disable the Read-Only Recommendation
Excel's save options include a check box that marks the file as "read-only recommended," which helps prevent accidental changes. When you open such a file, Excel asks whether you want to open the workbook as read-only or not. Excel won't prevent you from altering the file even if you pick "Yes," but when you save your changes, you'll have to create a separate copy. Click "Browse" on the "Save As" tab of the File menu. Before clicking "Save," press the "Tools" drop-down menu next to the "Save" button, pick "General Options" and turn off "Read-Only Recommended" to remove the warning from the new version of the workbook.
Turn Off the Read-Only Attribute
Any file on a computer can have the read-only attribute, which prevents programs from altering it. Unlike "read-only recommended," files with the read-only attribute enabled don't display a prompt when you open them in Excel, as you can't choose whether or not to respect the attribute. As with "read-only recommended," however, you can use "Save As" in Excel to create a new, editable copy of a read-only document. Alternatively, to unlock the original copy for editing, right-click the file before opening it, choose "Properties" and uncheck "Read-Only."
Work Around Protected View
As a security measure, Protected View prevents you from editing files that you download. When Excel opens a workbook in Protected View, it displays a notice at the top of the screen. Click "Enable Editing" on the notice to edit the file. To remove the flag on the file that indicates its online origin and triggers Protected View, right-click the file, choose "Properties" and click "Unblock." After you close the Properties window, you can't undo this choice.
Disable Protected View
In general, you should not disable Protected View, because it helps keep your computer safe. If you plan to open many spreadsheets from trustworthy sources on the Internet and want to avoid Protected View's hassle, however, you can disable the feature entirely across all Office applications. Click "Options" in Excel's File menu, select "Trust Center" and press "Trust Center Settings." Choose "Protected View" and turn off the check box for each instance that you don't want to use the security measure. After you finish your project, turn these settings back on to protect yourself in the future.
Some workbooks include protection that locks you out of editing one or more sheets. To disable this protection, open a locked sheet and click "Unprotect Sheet" on the Review tab. If the original author of the file locked the sheet with a password, you need to know the password to unlock the sheet. After making changes, re-enable protection by clicking "Protect Sheet" and entering a password, if desired.