check ignition switch as mentioned
check interior light fuse
check ignition fuse under bonnet fuse box
does it have instrument warning lights (reds)-does it crank at all
try poring hot water on
ecu wriggle connections at
ecu
does fuel pump prime when key turned on (possible fault with engine relay and or fuel relay)
is it in park
does it have a fuel cut switch at top edge of left hand kick panel
try to supply more detail - is it cranking and not firing -6 or 8- sedan _ did it over heat. etc