here the log; I don't think the REPAIR DISK option could solve the problem, or not ? :

Welcome to SFSDoctor - The Disk Recovery and Repair Suite
---
[00:14:31] Root block is damaged. Trying to use secondary one at block 38800356
[00:14:31] Both root blocks are damaged.
[00:14:31] No valid SFS directory structure found on drive Apple_HFS_Untitled_3
[00:14:31] Use 'Find Lost Objects' action to try to recover your data
[00:14:31] Done

[00:18:52] Preparing lost object search
[00:18:52] Found 38800354 blocks to check
[00:18:52] Searching for lost filesystem objects
[00:26:21] Joining object containers
[00:26:21] Creating directory tree
[00:26:21] Attaching extents to file objects
[00:26:21] Found 0 lost object(s) and fixed 0/0 damaged object(s)
[00:26:21] Checking extent tree
[00:26:22] Operation finished
---
[00:27:28] Released drive Apple_HFS_Untitled_3.
---
[00:27:45] Checking drive Apple_HFS_Untitled_4.
[00:27:45] Checking root blocks
[00:27:45] Error: cannot read rootblock at block 0
[00:27:45] There are errors in filesystem structure. It is advised to backup data and repair this partition
---
[00:27:53] Root block is damaged. Trying to use secondary one at block 25128481
[00:27:53] Both root blocks are damaged.
[00:27:53] No valid SFS directory structure found on drive Apple_HFS_Untitled_4
[00:27:53] Use 'Welcome to SFSDoctor - The Disk Recovery and Repair Suite
---
[00:14:31] Root block is damaged. Trying to use secondary one at block 38800356
[00:14:31] Both root blocks are damaged.
[00:14:31] No valid SFS directory structure found on drive Apple_HFS_Untitled_3
[00:14:31] Use 'Find Lost Objects' action to try to recover your data
[00:14:31] Done

[00:18:52] Preparing lost object search
[00:18:52] Found 38800354 blocks to check
[00:18:52] Searching for lost filesystem objects
[00:26:21] Joining object containers
[00:26:21] Creating directory tree
[00:26:21] Attaching extents to file objects
[00:26:21] Found 0 lost object(s) and fixed 0/0 damaged object(s)
[00:26:21] Checking extent tree
[00:26:22] Operation finished
---
[00:27:28] Released drive Apple_HFS_Untitled_3.
---
[00:27:45] Checking drive Apple_HFS_Untitled_4.
[00:27:45] Checking root blocks
[00:27:45] Error: cannot read rootblock at block 0
[00:27:45] There are errors in filesystem structure. It is advised to backup data and repair this partition
---
[00:27:53] Root block is damaged. Trying to use secondary one at block 25128481
[00:27:53] Both root blocks are damaged.
[00:27:53] No valid SFS directory structure found on drive Apple_HFS_Untitled_4
[00:27:53] Use 'Find Lost Objects' action to try to recover your data
[00:27:53] Done
---
[00:28:06] Preparing lost object search
[00:28:06] Found 25128479 blocks to check
[00:28:06] Searching for lost filesystem objects
[00:33:35] Joining object containers
[00:33:35] Creating directory tree
[00:33:35] Attaching extents to file objects
[00:33:35] Found 0 lost object(s) and fixed 0/0 damaged object(s)
[00:33:35] Checking extent tree
[00:33:35] Operation finished
' action to try to recover your data
[00:27:53] Done
---
[00:28:06] Preparing lost object search
[00:28:06] Found 25128479 blocks to check
[00:28:06] Searching for lost filesystem objects
[00:33:35] Joining object containers
[00:33:35] Creating directory tree
[00:33:35] Attaching extents to file objects
[00:33:35] Found 0 lost object(s) and fixed 0/0 damaged object(s)
[00:33:35] Checking extent tree
[00:33:35] Operation finished