If you have time tomorrow, let me just show you on my test server.
it will be easier in this way.

HE IS LITERALLY BACKWARD
not texture, not bone or any other stuff.
no nothing
Literally
Backward

more simple explaination: Moon walking

this model is from slender fortress.
It's scp 173.
but the problem is, when scp 173 is looking at me or at the front, his back is looking at me not his face.
model and texture is just fine.
this model has no animation,eyes,mouse,lips etc.
it's just a one simple model with one simple texture.
can you help me out???
i can send you a picture or invite you to my testing server to show you
i will send the files to you if you want to have a look

i watched your tut and tried editing the mdl file but i failed :/
it would be great if you could teach me how to edit model it self and safely save/export back to mdl file.

also, if i do this, i mean editing the back and front thing, do i also have to rematch the textures too?