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• Add new partitions in the (old) Windows part of your disk. The first one (i=4) is a new system partition, the second one (i=5) a recovery partition. The new OS X partition starts at ~91 GB and has a size of ~26 GB - which shouldn't affect the old (hidden, "lost") OS X partition:

    gpt add -b 180000000 -i 4 -s 50000000 -t 48465300-0000-11AA-AA11-00306543ECAC /dev/disk0
    gpt add -b 230000000 -i 5 -s 1269536 -t 426F6F74-0000-11AA-AA11-00306543ECAC /dev/disk0
  

• Now you have to format the new 26 GB partition:

    diskutil list
    newfs_hfs -v "TempSystem" -J /dev/disk0s4 #use the proper partition found in diskutil list. It should have a size of ~26 GB
    diskutil mount /dev/disk0s4
  

• Exit Terminal by entering exit and quit it.

• Open Restore OS X and install OS X to the partition TempSystem

• Configure the new system and enable internet access. Don't initialize any "unknown" volumes if asked.

• Enable the root user

• Log-out as admin and log-in as root

• Download and install wxHexEditor

• Where does the Recovery HD partition start?

  That's probably the most difficult part because you have to find a string which is not very specific. Jump almost to the beginning of your new main partition (in your case to sector 179999900)

  Then enter "HFSJ" like in the picture below, search for this string two times and make readable! hand-written notes of the different offsets. To restore your old OS X you have to boot to Internet Recovery Mode later and all on-screen findings in the current temporary OS X will be lost!

  The reason to search for the string "HFSJ" is that all HFSJ+ volumes contain this string in the third sector of its partition. The string may also occur later and at the end!

  

• Add new partitions in the (old) Windows part of your disk. The first one (i=4) is a new system partition, the second one (i=5) a recovery partition. The new OS X partition starts at ~91 GB and has a size of ~26 GB - which shouldn't affect the old (hidden, "lost") OS X partition:

    gpt add -b 180000000 -i 4 -s 50000000 -t 48465300-0000-11AA-AA11-00306543ECAC /dev/disk0
    gpt add -b 230000000 -i 5 -s 1269536 -t 426F6F74-0000-11AA-AA11-00306543ECAC /dev/disk0
  

• Now you have to format the new 26 GB partition:

    diskutil list
    newfs_hfs -v "TempSystem" -J /dev/disk0s4 #use the proper partition found in diskutil list. It should have a size of ~26 GB
    newfs_hfs -v "Recovery HD" -J /dev/disk0s5 #use the proper partition found in diskutil list. It should have a size of ~650 MB
    diskutil mount /dev/disk0s4
  

• Exit Terminal by entering exit and quit it.

• Open Restore OS X and install OS X to the partition TempSystem.

• Configure the new system and enable internet access. Don't initialize any "unknown" volumes if asked.

• Enable the root user

• Log-out as admin and log-in as root

• Download and install wxHexEditor

• Where does the Recovery HD partition start?

  That's probably the most difficult part because you have to find a string which is not very specific. Jump almost to the beginning of your new main partition (in your case to sector 179999900)

  Then enter "HFSJ" like in the picture below, search for this string several times and make readable! hand-written notes of the different offsets. To restore your old OS X you have to boot to Internet Recovery Mode later and all on-screen findings in the current temporary OS X will be lost!

  The reason to search for the string "HFSJ" is that all HFSJ+ volumes contain this string in the third sector of its partition. The magic string may occur up to 40 times cluttered over ~10000 sectors! Sometimes it's really difficult to find the proper sector. A second indicator for the beginning of the Recovery HD is at least one block of 0xFF in the tenth sector (or block(MagicString)+7) of the partition.

  

The volume (encrypted with FileVault) had a proper volume structure, the superior disk structure was corrupted though. After backing up the volume externally the disk was repartitioned to one partition and the backup was restored.

Work In progress

Windows' Disk Management has overwritten the GUID partition table with something unknown. This usually only effects the partition table but not the content of your disk (though it seems to be gone)! Aa proper GUID partition table has to be restored.

Windows' Disk Management has overwritten the GUID partition table with something unknown. This usually only effects the partition table but not the content of your disk (though it seems to be gone)! A proper GUID partition table has to be restored.