You plugged in your Tumbledryer and there was a bang and smoke from "the switch"....
Is that the switch on the wall where you plugged it in or the control switch on the tumble dryer?
Electrical smoke and bangs are usually associated with a short circuit where too much current flows - you may have a problem with the tumble dryer, the plug itself on the end of the cable or the socket you plugged into.
Put another working appliance into the wall socket and see if it still works. If the plug is the type with a built in fuse then check the fuse. If the plug is the type that you can take apart then inspect fuse and wires inside it.
If all these external things are good and working then the fault probably lies in the tumble dryer - your choices are to attempt diagnosis and repair yourself - call a repair engineer - replace the appliance.
Good luck...
Peccavi, May 2009