I have a Murray 12HP Lawn Tractor, (Model #282707)with B&S engine.There are safety switchs in several places on this mower, if you have a service manual, you can find them or look underneath and follow wiring. There is one under the seat on mine. Before you check for these remove the ground cable from the chassis (or where ever connected) clean this connection with coarse sandpaper and the area that it attaches to.
I'm not sure why the lights are not working--maybe burned out? or connector came loose from vibration?
Hope this helps!
Walt, September 2008
If you have no signs of life whatever, check the fuse!. There will be 1 or 2 fuses - either in a conventional fuse folder, or in a in-line type holder.