fuel finished when I was drivig , I got fuel on it now but it won't start

sometimes the car won't shift from 3,into 4,5,6,or7 gear. When I shut the car of and restart it goes back to normal. The check engine light does not nor is on

it doesn't want to start with ignition key.all this problem started when we removed gear box for repairs.when we traced ignition circuit key is supplying voltage to computer box,but computer box is not supplying starter

It has been regularly serviced by a main dealer - should this have been picked up