Create backups to revert from unwanted saved changes (Excel 2000/2001/2002/2003/2007)

When you're working fast, you're bound to make mistakes. You'll often catch your errors right away, but it's easy to make accidental changes to a workbook's existing data and not notice until it's too late. If you've ever felt the nausea that accompanies the realization that you've just saved workbook changes that unintentionally destroy large amounts of data, you should investigate Excel's backup feature.

Excel's backup capability provides a way to restore a workbook as it existed prior to when you last saved the file. Unfortunately, the feature isn't as easy to use as it probably should be--it's activated in an obscure manner and must be set up on a file-by-file basis.

You specify whether automatic backups should be created when you save a workbook. Once enabled, the setting remains active for all subsequent saves, unless you specifically disable it. To activate the setting in a new file, click the Save button or choose File | Save from the menu bar. (In Excel 2007, click the Office button and then choose Save.) If you're working with an existing file, choose File | Save As from the menu bar. (In Excel 2007, click the Office button and then choose Save As.)

When the Save As dialog box appears, click the Tools button on the dialog box's toolbar and select General Options from the subsequent menu. Next, select the Always Create Backup check box and click OK. Finally, name and save the file as you normally would.

From now on, Excel creates a backup in the same folder as the original file whenever you save the workbook. Instead of an .xls file extension (or .xlsx file extension in Excel 2007), the backup uses an .xlk extension. The .xlk extension is the same even for Excel 2007 files. Excel automatically names the backup by incorporating the name of the original file, using the format Backup Of Filename.

Keep in mind that Excel only maintains one backup file. Each time you save your workbook, the last backup file is overwritten with a new one.

To restore a backup, choose File | Open from Excel's menu bar. Then, choose Backup Files from the Files Of Type dropdown list, select the appropriate backup file and click Open. You can create a new workbook fro m the backup by choosing File | Save As and saving a regular Excel file.