There's usually a way to get at the bulb, sometimes you have to remove a plate on the outside. The bulbs often have an Edison Screw fitting, rather than the more common bayonet mount used in the UK, so it might just have come loose and just need tightening up.
Sometimes you have an access panel and others you unscrew around it and lift the entire case away. It is a small Edison Screw fitting which will be obvious. As long as you do not touch any other parts you are fine to change the bulb yourself.