Computers are complicated machines that have a mix of delicate and sturdy components. Almost all of these specialised parts can fail in one way or another, and when these malfunctions occur, it can be exceedingly frustrating, to the point where many people consider just throwing out their computer. This is especially true when the computer won't even turn on. Luckily there are many professionals in computer repairs that can diagnose and fix the issue with your PC in a couple of hours.
Broken Power Supply Unit
When a computer won't turn on in the first place, experts in computer repairs will look to the power supply unit. After all, this is where the power first enters the computer, so it makes sense that if the power supply unit is not working, the power likely will not get to the rest of the components. Often, it can be as simple as replacing a corroded wire or fried power supply unit, and the computer will work again. Do not try this replacement on your own: malfunctioning power supply units can easily electrocute you if you don't know what you are doing. They can also trip the breakers in your apartment or home, which is just a pain to deal with.
If your computer's fans are constantly running at full power (or not at all), then it is a sure sign that the CPU is getting way too hot. This is not natural, but it is a common problem with older computers. There are a few ways to fix this: add in new fans, replace the fans with a more efficient cooling system (liquid cooling), or replace the CPU. Sometimes the problem is actually a software issue, and part of the process of computer repairs is to rule out these possible problems one by one before you arrive at the one responsible.
Disconnected Internal Cabling
If your computer won't turn on but you never had any warning signs, then there is a possibility that some internal cabling wasn't up to scratch and some components were disconnected from each other. This often happens after a move, so if you have recently transported your PC somewhere and it won't turn on, this should be your first thought. Computer repairs encompass all problems, including disconnected cabling, and they will be able to find out what is wrong in short order. It can be hard for someone who doesn't know which cables should go where to fix this problem, even though it seems so simple. The last thing you want to do is make the problem worse by connecting two components that do not go together and creating an actual hardware malfunction.