In Microsoft Windows® Explorer, look in the XLStart folder, and remove or rename the book.xlt (to restore settings for workbooks) or sheet.xlt (to restore settings for worksheets) template file. The XLStart folder is usually at
C:\OS\Profiles\User_name\Application Data\Microsoft\Excel\XLStart
where OS is the operating system folder (for example, the Windows folder).

If the files aren't in the XLStart folder, look in the folder specified in the Alternate startup file location box on the General tab in the Options dialog box (Tools menu).

More information

For more information about troubleshooting templates in your Office program, type troubleshoot templates in the Office Assistant or on the Answer Wizard tab in your Office program Help, and then click Search.