I can’t tell you how many times I was asked this question when I worked in I.T.: “I accidentally just closed my spreadsheet and said NO to saving my changes…is it gone?” For whatever reason, some people’s fingers slip from time to time and the wrong button gets mashed. The shadow copies feature introduced in XP (aka “previous versions” in Vista) helped to some extent as does the AutoSave feature in Office. However, if you’re working with a spreadsheet undergoing a lot of revisions, what you might like even better is a tool that took periodic snapshots of the file at intervals you specify, allowing you to restore the spreadsheet to any particular moment in time.
As it turns out, there is a tool that does just that. I recently came across a review of it over on gHacks. The tool is an Excel plugin called Autobackup. With Autobackup installed, you can specify how often you want your spreadsheet backed up, how many copies it should save, and how long those copies should be saved (in days). Installation is simple – just got to Tools –> Add-ins and browse for the Autobackup file. Autobackup is available as a free download from here. An English and Portuguese version are available.