1987 astro van help!

i have a 87 astro van and i cant start the car and its not the battery i replaced it...i am not getting any power in the car (ex: lights, horn, pwr locks) they all dont work....it happened all of a sudden....any one know whats wrong.....if u can help let me know....need some suggestions on what it could be thanks

First thing I would check is the battery cables. Especially the positive cable down to the starter. You can check it by connecting a jumper cable from the battery to the large post on the starter. While your at it, run the other jumper cable from the battery to a good ground. Good luck.