If your light fitting stops working then it is really worth calling a professional out to take a look at it. The nature of the fitting makes them a little more complex to deal with than a switch or socket, but an electrician should be able to spot any problems and repair them quickly.
Most light fitting problems are down to damaged or ageing wiring, with wires often becoming frayed or disconnected from the fitting. In most cases the repair will simply be a case of repairing and replacing some wiring. Although, where the fitting is damaged, your electrician may suggest the need for a new light fitting.
Access to the fitting is one aspect of the job that can influence price. In most cases the electrician should be able to access the fitting easily. But if they need to go up in the roof or beneath floorboards then the job may take longer and cost more.