Are you encountering Mac error at startup and because of that the system is not booting. You are unable to access your files saved in the Mac drive. The reason why you are getting the error because the operating system is not loading in the memory, this can happen when the start up disk where the operating system files are stored has been corrupted. The cause of corruption can be that the system was abruptly shut down there was any improper partitioning of the drive, the drive is infected by virus and there can several other reasons that can be responsible for Mac error at startup. You can test the drive health with the help of disk utility which can fix some minor problems but not in all cases. You may have to format the drive and then reinstall the Mac OS X. Now the Mac error at start up is fixed then you may be interested in recovering the data. You can take help of the time machine and if it does not work then use Mac data recovery software that is capable of recovering each and every type of file that was erased while formatting. So you need to download and use the software now.