hi, obtain a replacement, switch off power via main switch on fusebox, test to make sure its off! disconnect old switch taking note of where the wires go markings are usually C (being the feed this may be cross linked to the other switch ) L1 & L2 (being the load or switch wire one or both might be used) tighten connections making sure there's no wire showing outside of the terminals. If the replacement is a metal switch (chrome, brass etc. this has to be earthed by connecting from the earth cables. carefully fold the wires back into the box and screw the switch back. if its right and there's no faults switches will be on when down (unless its a two way).
Rob, December 2007