My computer isn't booting.

ForceTorno

Honorable
Jul 9, 2013
2
0
10,510
Don't ask me about specifics, I just got into PC stuff. All I can really say is that it's a Thermaltake Commander MS-I by Cyberpower.
Anyway.
I used my computer last night and it worked fine. I turned it on this morning and now it's claiming that there's nothing to boot.
Here's specifically what happens:
I turn it on and the MS-I screen pops up. Then it moves to the first black and white screen showing some technical mumbo-jumbo, attached devices, "press CTRL-A to..." etc. Then it goes to that blanking white cursor on a black screen, right? Here's where things go bad. The blinking cursor sits there for a little then I see an extremely brief flash of "Graphics Card [something]" before looking an a non-blinking cursor on the screen. It stays there for a little while and then I get the banner for the hard drive with a prompt saying "Press any key to enter the boot menu" while a loading bar fills up. But whether I just let it load or hit a key, I always get the same thing: "No bootable device, press any key to restart".
I don't know what's going on or how to fix it.
Please, HELP!