stereo not working?

my wife has a 04 fiesta and her car stereo has stoped working for no reason!
the stereo is a 4500 rds e.o.n
i have checked the fuse that is in working order
and i can not find a inline fuse any wair.
there is power going to the conection so i am completely stumped can anyone help please.
or should i replace it many thanks.