hello! pls help!!!

ok i know this sounds kinda stupid but anyway..
there is this book i read last year... but could not complete it . i dont know the name of the book but here is a gist of wat i know abt it:

it is the diary of a girl called miranda ,she lives with here mother and her brother matt, her dad remarries and suddenly some comets strikes their place and nothing is in control.

if this rings some campana to u pls tel me the name of the book.(if u feel i am being stupid sry i wasted ur time).

thanks for answering.