Erasing and Partitioning Hard Drive from Internet Recovery
This sounds like your hard drive failed entirely. I see that it's a typical SATA drive in that model. You should be able to open it up and remove the drive, then wire the drive to a desktop and see if it is detected. If it is not, that confirms that the hardware failed.



Comment by OP: It turned out to be a SATA cable failure, see Hard Drive Issues with MacBook Pro 13-inch mid-2012.