How to Repair DMG Files
By Theon Weber
DMG files are Apple disk images--single files that represent the entire contents of a physical disk and can be "mounted" on a computer to provide access to that contents. Just like real disks, they can become corrupted and damaged, and are often difficult to fix. However, Apple's built-in disk utility may help you repair minor damage to a DMG file.
Open "Applications," then "Utilities" and double-click on "Disk Utility."
Drag the DMG file into the disk utility's left pane.
Select the DMG file you dragged in, click the "First Aid" tab, and click "Repair Disk." Follow the on-screen instructions.
Theon Weber has been a professional writer and critic since 2006, writing for the Village Voice, the Portland Mercury, and the late Blender Magazine. He was a staff writer at the Web-based Stylus Magazine from 2005 to its closure in 2007.