The lights upstairs don't work. They all went out this morning when I tried to switch one of the lights on. We have checked the fuse box and it appears to be working fine and none of the switches has been tripped. The upstairs lighting swith controls the understairs cupboard light and that is still working.

Thanks for your help.

Are your receptacles working and on the same circuit? Try opening the boxes starting with the one where you flipped on a light. Look for loose or disconnected wires. Test with a probe or meter for powerbetween the black and white and also between the black and ground.