If your Dell computer won't turn on, chances are there's a problem with its connection to its power supply. A lot of times, a Dell computer won't turn on because of something as simple as a setting on a surge protector to a tripped circuit breaker that cuts off power to the room entirely. Troubleshooting a Dell computer that won't turn on could save you a lot of time and energy in getting your PC checked out by a professional.
Reconnect your Dell computer's power cable to its wall outlet or surge protector and to the computer's system unit if the power cable is detachable.
Turn on the surge protector connected to your Dell computer. Many surge protectors have an "On/Off" switch that can cut the power to any connected devices.
Disconnect your Dell computer from its wall outlet or surge protector, and plug it into a different outlet.
Examine the power cable for any extreme wear or damage. Replace it immediately if there's any fraying or tearing. This goes for laptop AC adaptors as well.
Plug another appliance into the electrical socket, and see if it works. If it doesn't work, the outlet isn't getting any energy. Some rooms have a light switch that also controls the electrical flow to power outlets and needs to be flipped on for the outlets to function. Other times, you need to find your home's circuit breaker box and make sure the switch isn't flipped. Circuit boxes are typically found in your home's basement or garage near the electrical meter.
Contact Dell support if these troubleshooting tips don't work, as there may be an issue with your power supply or your computer's power button that needs to be fixed by a professional (see Resources).
Only use the power adaptor or power cord included with your Dell PC or a replacement of identical specifications.