I hardly know where to begin.

win 8 is not booting from HDD. linux testdisk shows no errors at all as does diskhealth, no errors! Having said this in gpparted I cannot mount it!
Also if I put it in a usb enclosure and connect it to my sony vaio it auto installs drivers but the drive is not visible and bizarely when I unplug it the OS asks for it to be formatted. The partition is EFI GPT. There are a number of volumes including one FAT32 for the efi boot info and one for the OS, NTFS.

There are applications on the drive in addition to the OS Win 8.0 (according to the laptop spec - not sure how I know for certain) and possibly some important data.

It's ueif bios (although I have had to turn off to get boot from usb repair media) I have tried to fix the ueif boot loader using bcdboot (correctly) but the bcd store in c:\windows\...\... is corrupt.

I am think I should repair windows itself to fix bcd store and any other parts of windows that may be corrupt.
I cannot download a win 8 iso only a win 8.1 iso.
eightforums tutorial says I should launch the setup app from a dvd burned from the win 8.1 iso.
I have no working os to launch that from though
I can only create a repair usb, no way to create a repair dvd I can see. I can only create repair media from a machine, cannot download one, even though AFAIK they are generic aside from recovery from a backup partition, the only properly "working" machine I have is win 8.1 not win 8, so recovery usb is 8.1. When I boot from recovery usb, after logo, it goes to blank (still running) screen and only occasionally does it go past this (after a very long time - what is it doing?) to offer actions. Why is this since I boot the same thing in the same way everytime!

Is it a problem that I have a win 8.1 recovery disk when the original win is 8 (and the product key)? Is this causing the blank screen?

If I boot from the dvd created from the win 8.1 iso, similar thing happens, startup logo and blank screen for a very long time (maybe not waited long enough yet in this case) why is this? Is it to do with the fact that original win is 8.0 and product key in bios will be for that?

HOW do I repair windows 8 and the boot loader so windows 8 can boot up from my HDD again.

Why can I not just get a win 8 install iso / disk, since my product key is in the bios what is the problem. If I can get that will I be able to just repair the OS and pleave the other files. Why does the 8.1 dvd hang with a blank scrreen? If I wait long enough will it eventually present some buttons like the win 8.1 recovery usb behaves?

Any advice welcomed.