In Macintosh once DMG file is not recognized in Mac, serious troubles occur which bother you a lot. Indeed Mac make use of disk image as DMG which play vital role in system overall functioning and it is essential that DMG file gets mounted. Unfortunately in some point because of certain known or unknown factors lead inconvenience situation wherein DMG file is not recognized in Mac. In consequence of that you can't access the system normally along with your important files turn inaccessible. For resolving this issue you can simply restart the system at first, other than that check disk permission issue through disk utility where repairing of disk can be done as well. If you can't resolve DMG file is not recognized in Mac then only option is left and that is formatting and reinstalling OS X. However this would turn into data wipe out situation which can be sorted out only after restoring Mac data. For this reason backup of data can be used but do not get fret if there is no such backup, luckily third party Mac Data Recovery Software makes it possible. This is proficient solution to recover formatted and missing Mac data. Thus you can overcome from DMG file is not recognized in Mac issue.