It causes great mental agony when your company suddenly doesn’t boot up, especially when you have your work pending and you need to get it done as soon as possible. Actually a lot of people suffered from this problem at one point or the other. But if you haven’t, well this is obviously your first time. Anyway, this post will help you troubleshoot a computer that refuses to start up. There are various problems that can cause a computer to not start and we have compiled a bunch of common problems that can cause this problem. Hope this helps:
Note: In the interest of your computers and your safety, please be advised that you should remove the power cord before removing any computer component.

• When you switch on your power button, if you notice that the fans/lights don’t run, then check if the power cords are working and properly plugged. ELSE, check whether the power button is fixed to the power slot on the motherboard.
• Most of the time, it is the RAM that causes this problem! You should try removing it and placing it in the same or another slot firmly and turn the computer on. If it still doesn’t work, then try replacing the RAM with another similar and compatible one.
• If the RAM doesn’t solve the problem, then it must be the motherboard! To check whether the mother board is working or not, you must remove the RAM in the motherboard and switch the computer on. If you hear continuous beep sounds, then your motherboard is working but if the beeps don’t come, then your motherboard is faulty.
• Even faulty PCI cards are sometimes the problem. So try removing the PCI cards one by one and turn on the computer. Using trial and error method, try finding the faulty PCI card and replace it with a new one.
• The power supply can also be the problem that won’t allow the PC to start. You should replace the power supply with an already working one and start the computer.