Why did my truck just stop running the switch turns but nothing?

Whooo one prob at a time, lights don't mater if it dont'run. It "cranks"but will not start..You are looking at a fuel or spark issue. It has enough fuel^, was it raining or wet, (water intrusion in ignition-spark- system). ok, fuel pump or distributor prob. Put your ear to the back of car at the fuel filler cap, have some one turn the key on (all the way to start, but don't start) you should hear the fuel pump Humm, Whine for 2 seconds, if not pump or relay.Under the hood is a single wire, all by itself, just there hanging out it has a lill connector on it - like it's supposed to be plugged in to something. Well, with key on take a piece of wire and stick it from battery poss to the end of wire, if pump runs, replace fuel pump relay, if not running, Have fuel pump replaced. Ok, spark- pull one (don't matter) plug wire from the spark plug, have some one crank car, if you can't hear and or see the spark / ticking Have the ignition system checked out. NOW you can do these checks.. you need a piece of wire (=12in long), someone to crank the car(even this can be done by one person, just LISTEN close as you turn key on or try to crank). A bit long but very easy to figure out WHAT. Now repairing (other than relay) needs a 'shop'. Good Luck,

Sorry but you replaced the dimmer switch because the tail lights didn't work? LOL

Take it or tow it to a mechanic or at least to someone who knows something about cars, actually anything.