Restart your system while holding down the C key while you will start the system from the inserted installation disc.

Insert your MAC OS X installation disc.

Start system from MAC OS X Installation Disc

Continue holding the keys until the system restarts and you hear the start-up sound for the second time.Ĥ.

Press and hold the Command-Option-P-R keys before the gray screen appears simultaneously.

If by performing the safe boot, MAC performs as expected restart the system again to check normally.

While starting your MAC again, immediately press and hold the Shift key.

Disconnect all the devices including the printers, external hard drives, and the Ethernet cables attached to your System.

If you are unable to shut down your MAC the normal way, then hold down your system’s power button for a few seconds until it shuts down. Disconnect the Network Cables and the Peripheral Devices

If you were not backing up then it may be possible to get the data recovered by locating a recovery company that can be Googled.

If the disk has failed, then the only option would be to replace the disk and recover your data to the new disk from the time-capsule or any backup device you may have been using. Step 3: Click on View and choose Show All Devices to list all detected disks and volumes.However, before deciding to go with the Genius Bar we have listed some methods that may get you back if the issue is not the disk failure. Step 2: Select Disk Utility from macOS Utilities window and click Continue. Step 1: Hold Command + R and start your Mac into macOS Recovery mode Lucky you, Apple has a built-in program to fix minor errors in the disk. If there’s something wrong about your startup disk, whether there’s no startup disk in the Startup Disk window or the disk is corrupted, it can result in Mac not booting up normally. Solution 3: Repair the corrupted startup disk

Click on the Restart button to see if it works.

Select the hard drive which contains the Mac OS.

Click on the Apple logo at the upper left, choose the Startup Disk.

The macOS Utilities window should pop up and that means you are in the macOS Recovery Mode.Release the keys when you see the Apple logo.Restart your Mac and immediately hold the Command + R keys.Shut down the Mac by force by pressing the power button for seconds.If the first solution doesn’t apply to you, you can fix the issue by rebooting your Mac into macOS Recovery Mode and then choose another startup disk.

Mac startup with question mark