My D2-310/D4-310/D5-300C hard drive has suddenly become inaccessible. How do I retrieve my data?

1. Turn off the device, reinstall the hard drive, ensure it is firmly in place, and then turn on both your computer and the device to see whether the hard drive is recognised; if so, the data on the hard drive can be read as normal.

2. If your device is in single-disk or RAID1 mode, you may remove the hard drive and insert it in an HDD enclosure to see whether the data can be read. If so, this suggests that the device, rather than the hard drive itself, is defective, and you will need to replace it. If not, this suggests that the hard drive is defective, and you will need to visit a professional data recovery provider to recover the data. In the latter case, there is unlikely to be anything wrong with the device.

3. If one of the hard drives in a RAID0 or JBOD mode is damaged, the data on that hard drive will be unreadable. You will need to go to a professional data recovery provider to recover the data across all the hard drives.