When backing up in QuickBooks Desktop for Mac, it creates a disk image (.dmg) file. Each disk image that QuickBooks creates includes a copy of your company file and Attached Documents Library (If you use and choose to back up your attachments).
To check the location where QuickBooks for Mac stored the backup, go to QuickBooks > Preferences > Backup.If the backup is not on the specified folder, go to spotlight (Magnifying glass icon) and search for files with .dmg extension.
Restore the Company file from a .DMG file
Double click the .dmg file. A new window opens the "Ghost" drive. Note: The "Ghost" drive displays the back up of your company file along with your attachments (if applicable).
Drag the company file (with .qbXXXX extension) to the folder where you want to store the company file.
Drag the Attached Documents Library folder (if applicable) to the same folder as the QuickBooks company file.
Click the copy of the company file saved on the desired location or go to File > Open Company.
Restore Attached Documents
From the QuickBooks menu, select Preferences and click Attachments.
Click Attached Documents Library menu and choose Select Existing.
Select the Attached Documents Library folder that you copied from .DMG file and click Open.
Close the Preferences window.
Restore a QBMB or MAC.QBB file
Copy the Mac compatible backup to the Mac Desktop.
Click the backup. QuickBooks should prompt you to restore the file.