Does Mac OS X Mountain Lion library folder missing instantly? Obviously this can cause some serious problem for smooth running of the OS X and other useful applications as well. Each operating system must contain a library folder that plays very pivotal role in proper functioning of operating system. So Mac OS X Mountain Lion is not beyond of this and has same library folder but at meanwhile there may Mac OS X Mountain Lion library folder missing due to some uncertain incidents including wrong third party installation, accidentally deleting folder and due to improper usage etc. Besides there could be other possible reasons of this mishap happening, as result you can't access your important files which is quite disappointing. However what you can do is to do take appropriate actions to overcome Mac OS X Mountain Lion library folder missing. One of the reliable way is look for data recovery which gone disappeared because of this catastrophe. To do that one can either take help of previous backup which is created through Time Machine. Else backup unavailability scenario you should go with Mac Data Recovery Software. It enables you to restore deleted, lost and any type of missing data efficiently.