When most people think about backups and restores, they think about recovering from a failed hard disk. By far the most common backup request, however, is to restore a file that has been accidentally deleted, edited, or corrupted. For example, while writing a chapter one day, the cat stepped across my keyboard, selecting all text, overwriting it, and then miraculously closing the document. I had to restore the file from a backup made the night before.

I suggest automatically backing up your computer nightly to an external hard disk. If you follow that advice, you can easily restore earlier versions of corrupted files. To restore an earlier version of a file that has been backed up, follow these steps:

1. Find your file in Explorer. Right-click the file, and then click Restore Previous Versions.

2. The Previous Versions tab appears. If an earlier version of the file is available, click it, and then click Restore if the button is available. For system files, you can click Open or Copy. If you don’t see any previous versions, you’ve never made a backup of this file (using Windows, at least). Before you can recover the file, you have to configure Windows to automatically backup your files.

3. The Copy File dialog appears. You can choose to overwrite the existing file or save the recovered file with a different name. Click Copy and Replace if you’re sure about it. If you’re not sure, click Copy, but keep both files. Your recovered file will have the same name with a “(2)” after it.

4. Click Finish.

The file will be restored to its previous state.