Other than sending the My Cloud out to a data recovery service (and paying a lot of money).
You can try removing the My Cloud hard drive from it’s enclosure and attach it to a computer using a USB to SATA adapter or a USB docking station or a spare SATA port on the computer. Because the My Cloud uses Linux you would need to either use Linux or install a Linux driver to your Windows OS. If the drive is accessible using Linux or a Linux driver you can copy your data off the drive to another location/drive.
