reversed the battery cabels

If you checked all the fuses and they are good, you make have burnt up some fusible links. A fusible link is a wire that acts like a fuse when a short is present. They are connected off of the battery and feed the some of the main circuits. Sometimes it is hard to tell if is blown just by looking at it. When they go, they can be discolored (black or burnt) and soft when you attempt to bend them. However the best way to test them is with a volt meter for a open. I know Nissan used them in their older cars but I don't know if your car has them or if they still use them.

[quote:e46ae74cdb="mini_vuk"]I made a stupid mistake. The battery on my Nissan 200sx 1995 and 2.0 has always been in backwards. I forgot one day and attached the cables in the regular, but backwards for my car way. So I connected the positive to the negative and so on. I heard some hissing and other noises. I couldn't realize what was wrong until it hit me. I reversed them and was able to start my car , the lights work, but nothing else. the windows, gauges, and radio have no power. I have replaces all the fusses that I can see. If you could give some suggestions of what to try next that would be great.[/quote:e46ae74cdb]

Follow the battery positive cable it will lead you to the power distribution box-open it up you will see the little colored square boxes inspect it you can tell when its blown thru the window.