Your hard drive has failed or your OS is corrupted. At this point do not run disk utility's repair disk until you verify the health of the drive. Try resetting the SMC and Pram to see if your computer will boot. If you can get the computer to boot run Smartutility to check the health of the drive. If the health is bad replace the drive. If it's good you need to boot the computer in recovery mode (command + R) to reinstall your operating system. Just a heads up if you cant get it to boot you may need to remove the hard drive and test it with a powered sata hub with another computer to verify the health.
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Your hard drive has failed or your OS is corrupted. At this point do not run disk utility's repair disk until you verify the health of the drive. Try resetting the SMC and PRAM to see if your computer will boot.
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If you can get the computer to boot run [https://www.macworld.com/article/1143561/smartutility.html|Smart Utility] to check the health of the drive.
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If the health is bad replace the drive. If it's good you need to boot the computer in recovery mode (command + R) to reinstall your operating system.
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Just a heads up if you can't get it to boot you may need to remove the hard drive and test it with an external 3.5" HD case either via USB or FireWire with another computer to verify the health.
Your hard drive has failed or your OS is corrupted. At this point do not run disk utility's repair disk until you verify the health of the drive. Try resetting the SMC and Pram to see if your computer will boot. If you can get the computer to boot run Smartutility to check the health of the drive. If the health is bad replace the drive. If it's good you need to boot the computer in recovery mode (command + R) to reinstall your operating system. Just a heads up if you cant get it to boot you may need to remove the hard drive and test it with a powered sata hub with another computer to verify the health.
[guide|6284]
https://www.volitans-software.com/apps/smart-utility/