Why do headlights and fuel pump not work?

Check your fuses. Your owner's manual will show you where the fuses are. Replace any that are "blown," that is, no longer conducting electricity. You can tell faulty fuses of the type in your Astro by looking at the loop of metal in the fuse. If it is broken, the fuse has blown. You can buy an assortment at any auto parts store. If the fuse continues to blow, you will have to research the cause. If you are not comfortable working on your van, or if you don't know about automotive electrical components, you will have to find a competent mechanic. Researching automotive electrical problems can take hours, although many are quickly solved. Mechanics will tell you how much they charge per hour; that may motivate you to fix the problem yourself, or you could take a long-term view and just chalk up the charge to the cost of possession of a vehicle.