Are you willing to repair unmountable dmg file? If your answer is absolutely yes! Then, you are lucky enough to reach the proper place. However, being a professional users we might be familiar with DMG file and its attributes. If you are the one who have the knowledge about DMG file then good, otherwise don't worry! As here you get complete information regarding DMG file and its recovery process. DMG file is the internal used Mac OS X image file that contains all the essential details like types of operating system, number of partitions, driver details, etc. Further, due to its better programming the file is more secure from malicious attacks. But, due to some epidemic like software crash, hardware issue, problem boot sector, partition table Map corruption, etc. the DMG file gets corrupted and become inaccessible. However, to over such situation and to repair unmountable DMG file one should make use of Disk utility. But, in case the tool also fails to rescue the problem. Then, the last option left with you is to go formatting option.
Note: Doing so will erase all the stored Mac files. So, it is advised to have a backup of your data files. If anyhow you fail to create backup then, the last option to retrieve lost Mac data is through the use of Mac data recovery software.