When troubleshooting electrical problems, I always start with the fuse box. Find your owner's manual and see which fuse is responsible for the power windows, dash lights, and other electrical components that are causing you problems. Next, pull those fuses and inspect them to see if they have burnt.

There should be 2 places for fuses. There is an under hood (main) fuse box and there is a kick panel fuse box inside the vehicle.

If you don't find the problem there, then you will need a wiring diagram for your car and a multimeter to track down the fault. This requires that you understand electrical systems. I generally recommend if you cannot fix electrical issues by changing fuses, then take the car to a professional mechanic.

Also, my personal experience with cars is many electrical problems are caused by electrical modifications. People often modify their cars by adding security systems and stereo upgrades. No one ever takes the time to properly solder splice the wires, and they generally tie into existing wires with no consideration for the additional electrical load that the modifications create. While splices may work when installed, over time, they can become corroded or loose and cause problems. Take a look at your wiring to see if it has been modified. You may need to remove the modifications.