Trying to repair my Windows 8.1 boot

A few days ago my Laptop crashed and refused to boot again. It gave me the 0xc000225 error message and told me, that there is a error in my bootfiles. The Laptop is a Toshiba Satellite Pro C870 which originally ran Windows 8 64bit, but was upgraded to Windows 8.1 64bit

First I tried to repair it with the help of an Windows 8 installation disk. I ran the bootrec commands in the console and also tried the standard startup-repair, but nothing could fix it. I then discovered this tool on the internet, which uses a modified Ubuntu-Live System with a preinstalled tool called "boot-repair" to fix boot sectors, but even it couldn't help me with the problem, although it claims to even repair windows boots.

After that I tried out lots of other things with the Ubuntu live system, like LiLo or the MBR-Package to restore my boot, but with none of them i managed to make the Laptop start up again.

The current state is the following: Windows does still not start and gives me the following error message:

Windows failed to start. A recent hardware or software change might be the cause. 

[...]

File: \EFI\Microsoft\Boot\BCD
Status: 0xc0000225
Info: Boot Configuration Data for your PC is missing or contains errors

I just tried to run the bootrec-commands again. They all worked fine, with the exception of the /RebuildBcd command, which just prompted me if i would like to add my volume C: to the boot, where i obviously answered yes, but just got told that:

The Volume does not contain a recognized file system

I also tried running bcdedit, but I got the error message

The boot configuration data store could not be opened. The System cannot find the file specified.

I slowly ran out of ideas and dont know what I can do anymore.

I also started a question in the Ubuntu-forum, going in more detail about the boot-repair-disk, but they redirected me here. Click me!

I hope you can help me with my Problem