is my altinator bad because all my lights cut off

You are going to need to do some testing with a volt meter. 1) disconnect the battery from the vehicle. Does it have 12 vdc? if no charge it. does it hold a charge for 6 hours? if no, battery needs to be replaced. 2) if battery is good connect it back to the car. Start the vehicle does it start? if no, check your fuses in the engine under the hood. Are all your fuses good then it may be a starter, they can be tested for free at Autozone. Does the vehicle start now, if yes then disconnect the battery. Does the vehicle immediately shut down without the battery connected? Then it is your alternator that is faulty. Autozone tests alternators for free. Hope this helps