Missing or damaged kernel

I was playing minecraft turned of my screen, and later when i came back it seemed like my pc had restarted itself because all the programs had turned of and i was back at my desktop. Then when i started minecraft again it kept crashing. Then my screen got blue and it said there was a problem and my pc had to be restarted. When i restared it said my operating system couldnt be loaded because a kernel was missing or was broken: File: \windows\system32\ntoskrnl.exe
Error code: 0xc0000221
After that i tried some tips form the internet and tried to use my windowsinstallation disk but when i started my couldnt boot form the windows 8 boot disk.

Any ideas?

Greetings Tim