The two possible solutions: a new hard disk or a new motherboard. Or maybe just reseat the cable between motherboard and hard disk.
Since you're inside the normal year warranty (maybe you have even 2 years) it's clear what to do: back to the shop or to Acer Customer Service and have it repaired.
There's a good chance you'll lose all data on the hard disk. But you made backups, didn't you?
I have a Acer desktop, model X3470, bought it in December of 2012. Last week I turned it on in the morning and got a black screen with a message saying "Reboot and select proper boot device or Insert boot media in selected device and press a key." No matter what button I press I just repeat the message. I can't do absolutely anything from there.
How do I fix this?
Thanks for any help.