Thanks to Procyon for this answer. Seeing so many related questions I think Vita's "failed to load' message is common.  Searched through many answers. This is the one that worked.

Hi, i realise this is an old thread, but thought it may be worth sharing a possible solution for future readers!

Here is a possible solution that i worked out for the MusicMaker 2013 Premium Magix "Vita could not find the file not found VST Instruments" error.
A video i made of the solution is on Youtube -

An error was coming up after i installed Magix Music Maker 2013 (this may apply to other versions to?).
The VST Instruments would not load.
Vita reported a file could not be found - YT-MX SD 01 OH 01 XC#1 Y02 in image file Vita Rock Drums/Vita Content - How do you want to proceed?
The solution i worked out concerns the "settings.cfg" file in each of the VST Instruments folders.
Vita checks for the file path to load from, in my case the path was not correct.

The specific line in each of the settings.cfg files begins with
"user folder=".

This "user folder=" line must be set right to the specific folder for each VST Instrument.
For example in the Rock Drums folder, the settings.cfg file had the line - user folder=E:\MusicMaker\content\MxSynth\Rock Drums

There was no such directory on my harddrive!
So i used Windows Explorer to search for "MxSynth" on my E: drive (the drive where i had installed MusicMaker originally).

Windows Explorer found lots of files in E:\Soundpools\MxSynth, so i edited the "settings.cfg" file to read -
user folder=E:\Soundpools\MxSynth\Rock Drums

....and it worked!
You need to change the "user folder=...." entry in each "settings.cfg" file in each of the folders under, or in, the MxSynth folder.

Hopefully the video may help you to fix this problem.
Just to clarify, i'm not a professional at this!
Sorry if my explanation is not good enough for you.
So, step by step, this is (roughly) what i did -

1. Open windows explorer and search for the folder "MxSynth" in My Computer.
The results of the search should list lots of files in mostly the same directory.
In my case the location was - E:\Soundpools\MxSynth
It will most probably be different for you!
You have to remember this perfectly, so copy it!
2. Open windows explorer and navigate to -

C:\Program Files (x86)\Common Files\MAGIX Services\MxSynth.
There i found 5 sub-folders in my MxSynth folder called,
Bass Machine
Rock Drums
String Ensemble
Vita
World Percussion

2. Go into the first folder, in my case Bass Machine.
In the Bass Machine folder is a file called "settings.cfg"
Right click on this file and choose "copy".
Right click in the folder and choose "paste".
(we do this to have a backup of the original file in case we mess up!)
3. Next we open the "settings.cfg" file with the Microsoft Notepad program.
To do this we right click on the "settings.cfg" file, choose "Open with..." and choose Notepad.

4. Look for a line that begins with "user folder=", it was the 3rd line down for me.
Change this line to use the location you found in the step 1. search.
eg,
my original line was -
user folder=E:\MusicMaker\content\MxSynth\Bass Machine

my search from step 1. was -
E:\Soundpools\MxSynth
so i changed the line to read -
user folder=E:\Soundpools\MxSynth\Bass Machine

Do you see the difference?
Then, save the file.
----------------
Repeat 2. to 4. above, ie do the same thing to the "settings.cfg" file in each of the folders inside the MxSynth folder.

Finally, run Magix Music maker and try loading the VST Instruments.
Vita should no longer report an error, unless this was not the cause of the problem of course!

Hope this has helped you.