System failure, cant boot from SSD, data recovery

Hi guys,

A customer brought an mac pro 13" early 2015 modell.

The macbook can not boot, we tried boot from usb drive, and check the ssd with disk utility, but we got error 8 in the first aid.

after we connected an external hard drive with other osx (yosemite) in usb port, and the macbook booted properly. We check ssd drive, we see any folders, but when we enter the users folder, the folder is empty.

Users folder has most important files for our costumer.

Pls give me advice what a problem, that we could not see this folder's content.

Thank you

Tibor