windows 8 - Restore MBR and get everthing to its default

im on a cricital situation, i am not able to boot into my win 8 after i wanted to instal win u7 on a other hdd, something went wrong and when i removed my windows 8 hdd, windows 7 did not wanted to boot. if i put it back in, it will boot... Also the boot entry changed, i got windows 7 and Windows 8 as choice.

Now the big problem... Since 3 monts ago my USB Controllers has fried (when my old PSU failed) after placing the new PSU, shit happend, and i was not able to use my USB controller, i am really pissed off when this happend. i contacted the manafactur, but they didnt know what to do for me...

Anyway... What i am trying to say: I am not able to enter BIOS and or use keyboard/mouse while the pc is booting (once the windows loaded, it dedects my PCI card with usb ports on it, and the mouse and keyboard works finnaly...

so now the problem, since i am not able to use mouse and or keyboard, on the boot i cant choose Windows 8. The default mode is Windows 7 (but remember, i deleted the hdd where win 7 was) so after 30 sec, it enters automaticly windows 7 and gives me error messenge, and this repeats all over again.

I have tried my own ideas (starting from CD (disconnecting HDD first)) and then useing the bootrec /Fixmbr /Fixboot /rebuildBcd all worked fine except the last one, it gave me access denied or something like that. Then i suddenly rememberd, that Windows 8 had a special funtion when shutting down, it hibernates instead of shutting down (if im right...) So i said, damm you microsoft :D then i went a step further, i used my HDD where i installed Linux (i only use it for emercy situation like now...) the linux is up-to-date, always was carried good. i WAS able to mount this hdd but i could not find where the boot entrys are...

at this time i was really tired and i wanted to rest, i am doing this like almost 6 hours...

please somebody, if you got some ideas that might be usefull for me write it down please, i respect any reply's!

PS: Remember, i cant use keyboard and mouse on startup and not able to enter BIOS. I remeber that boot order was HDD>>CD-ROM>>Removeable devices(USB?)

Thanks already! PPS: there might me some grammer faults, its because i wrote it very fast....

Booted from Windows CD go to command prompt:

bcdedit /enum OSLOADER /v

this will output loaders for Win7 and Win8. Now see the ID's (and copy them).

bcdedit /delete {ID of Windows 7} /f (delete loader for Windows 7)

bcdedit /default {ID of Windows 8}

This will set Windows 8 boot by default.