You turn on the computer and nothing happens

No lights, no beeps, no fan noise. What is the first thing you do? Be sure the darn thing is plugged in!Even if you're absolutely certain that it is connected, double check. Assuming that it is plugged in, you probably have a bad power supply. This is a metal box located in the top and back of the computer. It is usually held in by four screws and the power cable connects to it. A fan blows air out the back. A wiring harness exits the power supply inside the computer. Numerous power connectors are attached to the ends of the wires. These plug into drives, fans, and possibly other gizmos. The harness also will have connectors to the motherboard. It doesn't matter which wire connects where, as long as the connector fits. When you open the computer, this mess of wiring can be very intimidating. Study it, and you'll find it less mysterious. Note the connections in writing, if necessary. Disconnect the wires and remove the power supply. Take it to the computer store and get a replacement with the same wattage. Figure on spending $50-70.