The most common case: Collapsed lower part of the button.

In the presence of details the bottom of the buttons with a diameter of 7 mm.

Herself button has an inner diameter of 8mm.   
Details of the buttons between them absolutely nothing in common, no need commit button.

Carefully parsed oversnow click on the reverse side, that would not damage the front part of the button. 
    Several times compressible bocaraton (not to stop), but after each compression rotatable bacares 90°. And so gradually, the button will collapse. The result is a shapeless piece of metal and an undamaged front part of the button.  
Then carry out the installation key (see the scheme above)

Another example:

In work commissioned order. Lost the lower part of the button because of a manufacturing defect. The order is not complex, but have only the details of the buttons smaller.
 
For the beginning of the parse button.
             
As the front part of the button is made of cast metal, it is not deformed and is suitable for re-installation. To install the button use available parts.
 
Then set the bottom detail  
And the product is ready      
The appearance of the jacket saved in its original form.

Note: If you have destroyed the front part of the button placket products in exactly the same way it can be restored, if it is possible to remove a key from a pocket or sleeve. To move it rather than get on a strap, and this is the place to install buttons from those that are available.

Note: generally, the internal diameters of the front parts of buttons (Cap) differ from each other slightly, 1-1,5 mm, So having only one diameter of the button you can change and repair virtually the entire spectrum of luverne buttons.  

  Happily for Russia, but these products to be repaired still have.
But if you meet the product lowername buttons smaller than the standard size, you probably need to completely change button.

 Another problem: Replaced the lower part of the button, but still weak fixation.
You can do the following. Without disassembling the upper part of the button, pressed it on the reverse side. 

  Squeeze them gently, trying what would pliers does not come off button, otherwise there are scratches.     This operation should be performed only when the difference in the diameters of the parts just a few tenths of a millimeter. When quite a little bit loaded and ready.

If you really do not have the appropriate details, and hold weak, then at least use the combined method. Biasing the annular portion of the button 
and slightly replusive the lower part of the button.        
If this method did not help means this method of repair are powerless, have to completely change the button on any available.

By the way, flattening the bottom of the button will not help if the lower part of the button from cast metal
                 Such getlucky often fall apart. Again to fix the still darkness.

It is necessary to combine the available details buttons. For example like this.

 Rarely, but there is a case when luverne buttons are set as hidden

     
       Set button, usually on one layer of fabric, without additional reinforcement. Work more on tailoring repair.