hi guys any advice would be greatly appreciated i am helping friend with her house and i have aproblem in her kitchen she has four of those eyeball downlighter type lights and they are not working they all went out at same time i checked wiring at 2 way switches and it was o.k. disconnected eyeball fitting put wand and test screwdriver on end of cables and both lit up when switched on so thought problem was with fitting so connected old type bayonet fitting and put in standard bulb just to test still not working i am baffled as power is on to end of circuit but lights still not working thanks in advance for any help guys.