My computer wont go past black screen w/ blinking underscore NEED HELP

[HIIMDAVID]

I dont know where I should post this so sorry but here's my problem.
So recently, my mother was using my computer watching a movie and all of a sudden it just shut down by itself. When she tried to turn it on, it showed a weird screen that i've never seen called "American Megatrend" bios thingy and it just ran through the whole system specs and etc. After that, on the bottom left it would say "Press [ESC] to boot" so she pressed boot and it looked as if the pc had just restarted itself and she heard the pc power up beep sound and the screen just went to a black screen with the blinking cursor. I tried pressing F12 to open up the BIOS Config thingy and it showed three. When i tried to chose one, it just went back to the beep sound and black screen w/underscore. We have a All-In-One Gateway Model # ZX4951-33e. I also tried inserting the system recovery discs my mother made before all this happened but they wont boot up. It would do the same thing, show the american megatrend screen and run through the specs and countdown from 9 to press esc to boot and after that, Beep, black screen with blinking underscore.
Please help us, we dont want to end up buying another pc and Im not really good with computers (neither is my mom)

 

[inzone]

If when booting there is an option to see the boot options , usually f-8 then you can see if the hard drive with the OS on it is the first boot option and if it isn't then you can change it to the right one.