macOS – Reset Mac and Can’t Reinstall macOS

In my opinion, Time Machine is the best solution. If you do a full restore from backup, all your configurations are retained. You'll need to enable FileVault after the restore is finished. If you do a nuke-n-pave and a pristine install, migrating profile data, apps and settings invariably misses some stuff, e.g., VPN configurations, automatic wifi connections, current RVM environment, 3rd-party printer drivers, etc.

If you repartition the drive and lose the local recovery partition, internet recovery will be slow; as such, you may wish to download your OS X version from the App Store and use DiskMaker X to create a bootable installation USB or DVD from which to proceed. Note that a local recovery partition is not created unless you do the actual OS installation first, which'll burn a good 30 minutes of your day. After that, you can reboot to the USB and head into the restore process.

You probably repartitioned the main volume the wrong way. At least your CoreStorage Logical Volume Group got corrupted either by partitioning or by "repairing".

The ultimate method to reset the drive is to completely destroy the GUID partition table of the main internal disk. This will render all data on the disk useless and you need an up-to-date backup to restore your old volume.

To destroy the GUID of your internal physical disk you have to boot to an external boot volume. This may be a OS X installer thumb drive or Internet Recovery Mode (which net-boots to a recovery image provided by Apple over the network). You mustn't boot to Recovery Mode which loads a basic system in a mounted but compressed recovery image in your recovery partition diskXs3).

• Detach any external disks - especially your Time Machine backup drive
• Boot to Internet Recovery Mode
• Open Terminal in the menubar Utilities -> Terminal

• Get an overview (especially the gpt command is important!):

  diskutil list
  gpt -r show disk0
  gpt -r show disk1
  

  Check which of both disks is your internal disk. Usually the internal disk is disk0 and the recovery volume is disk1 if you have only one disk in your Mac. In rare cases disk1 is your internal disk and disk0 is the recovery volume. The recovery disk has ~ 2600000 blocks (or ~1.3 GB). Even the smallest SSD is much larger. Below I assume your internal disk has the disk identifier disk0 - so use disk1 (or disk2, disk3) instead of disk0 in the commands if you find an other disk identifier for your internal physical disk.

• Unmount disk0:

  diskutil umountDisk /dev/disk0
  

• Delete the GUID:

  gpt destroy disk0
  

  If this doesn't help, then the hard way:

  dd if=/dev/zero of=/dev/disk0 bs=512 count=40
  

• Create a new GUID partition (this also creates a fresh pMBR):

  gpt create -f disk0
  

• Enter exit and quit Terminal.
• Open Disk Utility and partition your internal disk: one or two partitions and at least one JHFS+ volume.
• Quit Disk Utility
• Attach your Time Machine backup drive, open Restore Time Machine backup (or similar) from OS X Utilties and restore your backup.

This usually won't restore your Recovery HD. You have to do this either manually with Recovery Partition 4.0.4 or by reinstalling your current system with an Apple system installer (i.e. "Install OS X Yosemite" 10.10.5, which usually won't affect your data)