RE riding mower problem: Since the mow...

RE riding mower problem: Since the mower started fine and brakes also worked fine until, while riding it brakes stopped working and next time I tried to start it it wouldn't start I assume the problems are related as opposed to separate. I don't know were the switch for the brake/clutch pedal is located. The only hint as to the problem was finding the spring (probably half) on the lawn. Unfortunately the owner's manual is not too specific for me. Accordingly I posted here for help with diagnosis and repair.