Zyxel Auto Repair deleted all files

I had 2 disks in a RAID config working as a mirror for each other to prevent possible failures.

One day, my NAS 326 started beeping out of nothing so I followed the steps below:

1. Pressed the reset button
2. Went into the Admin area and checked if the disks were ok.

There was a message saying one of them was "degraded" so I clicked the repair button.

Now all of my files are gone. 

Can't see any of them!

What should I do?

In the end, both of my  WD Purple-line Disks were perfectly fine. I ran a scan and both are healthy.

Yet, 1TB of data, family pictures and files are gone.

Pls help!