To all you moms: what kinda advice or ideas can you give for a child's behavior I'm having a hard…

To all you moms: what kinda advice or ideas can you give for a child's behavior I'm having a hard time getting my child to listen and behave, ever since my miscarriage and her changing schools she has fallen out, I get phone calls from school, anyone deal with this before.. I feel like I'm about to break down and loose it..