Recovery options

When quick fixes don’t work, all is not lost…

If your Mac is unresponsive or exhibiting problems that can’t be resolved using the tips in the previous section, use your Mac’s diagnostics tools to check for physical problems before contacting Apple for support.

First, eject and detach all external devices, then shut down your Mac. Power on your Mac and hold d while it starts up until you see either Apple Diagnostics or Apple Hardware Test. (If you’ve completely erased your Mac’s startup disk in the past, you can start Apple Diagnostics from the internet by holding Alt+ d instead.)

On Macs introduced in June 2013 or later, your Mac will run Apple Diagnostics. When finished, either return to macOS if no problems are found, or restart in macOS Recovery (hold

ç+r), a hidden partition that enables you to repair certain problems or reinstall macOS.

Macs introduced prior to June 2013 use Apple Hardware Test. If this utility finds any problems, it gives an error code for you to quote to Apple or an authorized service provider when seeking their assistance. If your Mac shipped with OS X 10.7 (Lion) or an earlier version, you’ll need to use the diagnostics tools supplied with it – on Applications Install Disc 2 or the MacBook Air Software Reinstall Drive. They’re accessed by inserting the original optical disc or connecting the USB drive to your Mac and then following the same steps described to the left.

Repair in the Recovery system

If you are running OS X 10.10 or an earlier version, have tried repairing permissions in Disk Utility as described in the previous section, and it hasn’t solved your problems, repeat the operation after starting up in OS X Recovery, which you can enter by holding

ç+r at the startup sound. Select Disk Utility from Recovery’s main menu and repeat the repair process. Recovery also lets you reinstall the operating system from scratch. This will give you the most recently installed version of OS X if you use the local Recovery partition, or the one that shipped with your Mac if you use Internet Recovery.

Recovery also provides an option to restore your Mac’s contents from a Time Machine backup (provided you haven’t excluded system files from your backups). Any of these methods is an effective means of solving most problems, but will lead to data loss if you don’t have a recent backup.

If you’re suffering from persistent kernel panics, in which the screen dims and is overlaid by multi-language messages, or your Mac is forgetting small but important details between sessions, such as preferred volume or startup disk, reset your Mac’s NVRAM (non-volatile random-access memory), which stores key settings.

Power on your Mac and hold ç+ Alt+ p+r as soon as you hear the startup sound until you hear the sound a second time, then release and allow startup to complete. The 2016 MacBook Pros don’t have the startup chime – hold the