You can use AutoRecover to have Microsoft Office Excel automatically save a backup copy every time that you save a workbook. The backup copy is a copy of the previously saved version of your workbook. As a result, you have the current saved information in the original workbook and all previously saved information in the backup copy. Each time that you save the workbook, a new backup copy replaces the existing backup copy. Saving a backup copy can protect your work if you accidentally save changes that you do not want to keep or delete the original file.
Click the Microsoft Office Button , and then click Excel Options.
In the Save category, under Save workbooks, select the Save AutoRecover information every check box.
In the minutes box, type or select a number to specify the interval for how often you want to save files.
Tip: The more frequently the files are saved, the more information can be recovered if a problem (such as a power failure) occurs while a file is open.
Note: AutoRecover is not a replacement for regularly saving your files. If you do not save a recovery file after you open it, the file is deleted and any unsaved changes are lost. If you save the recovery file, the recovery file replaces the original file (unless you specify a new file name).