Rover 25 when ignition turn on warning light or wont start

Need to supply more info .If ignition light on and not turning over , try jump start .

make sure the batery is fully charged.check there is a live feed on the trigger wire on the starter motor when the key is in cranking position,there should be a permanent live.if there is a live feed at the trigger wire then suspect the starter motor.you can bench test the starter motor to check it,