Are you facing some problem in your Mac system ? Is it not booting at all and showing different screen ? There may be some internal corruption issue that is causing this trouble. You need a recovery disk Mac that can be used to reset the system and then bring it to previous working state. It will be the time where you have created the recovery disk Mac. It can be at the fist time you have opened the Mac system or the further timeline. However if the recovery disk is not available then you will have to format the system drive and reinstall the Mac OS X. The Mac will be restarted again but there will some data loss in both cases. You can get back the files with the help of the time machine backup which has the copy of the files saved in the external drive. But if the time machine is not working then you can use the Mac data recovery software. The software is designed with great sophistication and has advance algorithm which will scan the recover the files from the Mac drive with great ease. You should download the software now and use it for complete recovery.