Question

what happen plasma membrane breakes

Answer 1

if the plasma membrane ruptured then the cell  will die
the plasma membrane regulates the movement of substances in and out of a cell by diffusion or osmosis 
thus if plasma membrane is ruptured then the cell might leak out its contents  

Answer 2

If the plasma membrane breaks the cell will not be able to exchange materials from its surrounding by any means like diffusion or osmosis and hence the cell will die. so the brakdown of plasma membrane marks the death of cell.