Issue with available space

[Ireal123]

Ok, update !

Now that error disappeared but i got the following message

---

diskutil resizeVolume /dev/disk0s3 650M

Resizing to 650000000 bytes

Started partitioning on disk0s3 Recovery HD

Verifying the disk

Verifying file system

Checking Journaled HFS Plus volume

Invalid B-tree node size

The volume could not be verified completely

File system check exit code is 8

Error: -69803: Couldn't modify partition map because file system verification failed; please verify and repair each volume individually and then try again

 

[MRxROBOT]

Okay try this

diskutil repairVolume disk0s3

Tell me the output

 

[Ireal123]

diskutil repairVolume disk0s3

Started file system repair on disk0s3 Recovery HD

Repairing file system

Checking Journaled HFS Plus volume

Invalid B-tree node size

The volume could not be verified completely

File system check exit code is 8

Updating boot support partitions for the volume as required

Error: -69845: File system verify or repair failed

Underlying error: 8: POSIX reports: Exec format error

 

[MRxROBOT]

Lets try something via the recovery partition.
Reboot and hold command-r at startup to boot to the recovery partition.
Under the Utilities bar, you can open Terminal.

Enter

umount /dev/disk0s3

and then

fsck_hfs -r /dev/disk0s3

Once that completes restart your MacBook normally and follow the steps here again.

 

[Ireal123]

Lets try something via the recovery partition.
Reboot and hold command-r at startup to boot to the recovery partition.
Under the Utilities bar, you can open Terminal.

Enter

umount /dev/disk0s3

and then

fsck_hfs -r /dev/disk0s3

Once that completes restart your MacBook normally and follow the steps here again.

While running this

umount /dev/disk0s3

i got this error

 (/volumes/image volume): Resource busy -- try "diskutil unmount

i tried this

 disutil unmount /dev/disk0s3

and got this error
[Code]Volume Revory HD on disk0s3 failed to unmount: dissented by PID=0 (kernel)

tried to run your second code anyway and got this error
*[Code] /dev/rdisk0s3
Executing fsck_hfs (version hfs-305.10.1).
** Checking Journaled HFS Plus volume.
Invalid B-tree node size
(3, 0)
** The volume could not be verified completely.

 

[MRxROBOT]

The Invalid B-tree node size response was a sure sign that it was too far gone. I just wanted to give it a second run through in vain. Some people have had luck with Disk Warrior, but with the $119.95 price tag you're probably better off buying an external for considerably cheaper. In doing so you can create an image of your OS partition, format the drive, reinstall 10.11 fresh and restore said image. This will restore your missing space while preserving your OS and files the way you have it now.