In order to access the files on your Mac you will usually need to have a functioning version of OS X, along with a working display so you can interact with your system. From here, you can either use file sharing on the local network to access your data, or copy your data to external drives. However, if your Mac will not boot, or its display is not working properly, then you still may be able to get your data off of it.
The solution here is to have another Mac handy, and then start the faulty one in Target Disk Mode. This mode starts the system to a basic hardware level that in essence turns your Mac into an external hard drive. From here, you can use a Firewire or Thunderbolt cable to connect your system to another to access your data:
- Attach your Mac to another one using a Thunderbolt or Firewire cable.
- Start up your Mac while holding the T key.
Special boot modes on Macs require the system capture the keys being pressed before the firmware passes control to the operating system. This window of opportunity is immediately when the system’s boot chimes sound, which is also when the controllers for bluetooth keyboards are activated. This means that for wireless keyboards, you may have trouble activating Target Disk Mode as you will have to press and hold the T key immediately when the boot chimes sound, as opposed to before. Therefore, if you are having trouble getting your system into Target Disk mode, then try using a USB keyboard and holding the T key from the point you power on your Mac.
If your Mac is still not able to get into Target Disk mode, then you either have a firmware password set on your system to in part lock out special boot modes, or your Mac is experiencing enough faults that Target Disk mode cannot be accessed. In these cases, you will need to take your Mac in for servicing.
If your Mac is able to get into Target Disk mode, then it will show up on the second Mac as an external hard drive, and only require you supply a password if FileVault encryption was enabled on the faulty Mac. Once the drive is unlocked and mounted, you should have full and unrestricted access to all files on it.