Mirror Modifier - bad result


Everything that i try to use mirror give me a bad result:

How i can fix it?

Are you using multiple modifiers?

Supply a demo blend file as the info supplied is insufficient

No, there no others modifiers in this mesh.
You ask for a blend demo file?
Sry for my bad english

Yes, just an image is pretty much worthless

There is, thank you in advance.

I think I realized where the error is.
there a option called “Auto Smooth” in “Data” tab, i am right?