Whenever there is an issue related to Mac hard drive, disk utility has to be used first but what if disk utility fails to fix Mac OS X. Disk utility is the inbuilt tool to perform various types of functions like repair disk, repair disk permission, S.M.A.R.T. and make Mac OS X function properly again. Status and many more. Disk utility has many limitations though it can not repair directory structure, it only verifies the active start up disk. You can verify or repair the system file permission of the start up disk but it is not necessary that the system will boot normally. When disk utility fails to fix Mac OS X you may have to do it manually or you have to re install the Operating system. By doing so the Mac may boot up normally but you will notice that all the other data have been deleted. You should perform the recovery process immediately if you want it to be completely successful otherwise the deleted files may get overwritten. You may try to use any personal back up or the in built Time Machine back up. If there is any problem with the Time Machine back up you can always use Mac data recovery software which will restore any data which is deleted or corrupted. You do not have to worry when disk utility fails to fix Mac OS X, by following above suggestion you can bring your Mac in the previous state.