Get him to see if his neighbours have got power, simply by looking to see if there are lights on in their houses. If all of the houses are dark, it's a supply problem. (The power company will almost certainly know about it but phoning them to check won't do any harm).
If it's only his house that's lost power, the main circuit breaker might have tripped out. He should look for it, next to the meter, to see if it can be reset. If resetting it results in it immediately tripping out again, there's something that's shorting somewhere in his house. He should unplug everything, and turn everything off (including anything like an immersion heater, which is often the cause of such problems) and try resetting the circuit breaker again. If the power then stays on, he should commence plugging things back in, and turning them back on, until the power trips out again. He'll then know where the fault lies.
The above assumes that his home has circuit breakers in the consumer unit, rather than old-fashioned wire or cartridge fuses, though. It's not quite so easy to check things if there are no circuit breakers.
If the problem is within his own home (rather than a power supply problem to the neighbourhood), it's highly unlikely that his power provider will provide any assistance. He'll need to phone an electrician to help him sort out any problem that he can't deal with himself.