Windows 7: BOOT MGR image is corrupt error URGENT!! (not BSOD but help please)

I installed windows 8 transformation pack (i know im stupid) and after restarting it says
BOOT MGR image is corrupt The sytem cannot boot

i know that you can fix this problem by inserting windows 7 CD and just fix it there, but the thing is that if i choose 'Onboard or USB CD-ROM Drive' on bios it says 'Selected boot device not available. strike f1 to retry boot, f2 for setup utility press f5 to run onboard diagnostics.




*** i did not insert windows 7 CD because i dont have it right now but i will have it by tomorrow, but i did insert Windows vista CD just to check, but i dont think my computer can boot from CD. it just says the same error over and over! please help i think im gonna go crazy