Hello, my name is Dustin.
We should consider the possibility that the hard drive has either failed, or it has slipped loose from its connector.
Have you tried removing the hard drive? Here is a video that shows how to disassemble a previous model.
So disconnect the power cord, turn it off.. Then remove the hard drive.. Then,reconnect the hard drive.. And then turn it back on.
If it still doesnt work, you will need to replace the hard drive, then reinstall windows.
Your machine shipped with a 1 terrabyte hard drive.. If you wanted to double your storage space, you can get compatible hard drives below.
2 TB ( double your previous space ) http://amzn.to/2g8tfOR
1 TB ( same as your previous space ) http://amzn.to/2ff3cXx
Discount drive, various sizes. http://amzn.to/2g8scys
After you have replaced the hard drive, you can use another computer to download windows 10 to a USB drive using this media creation tool
Then, you will be able to reinstall windows on your new hard drive.
If you have any questions or concerns, let me know.