There are many reasons why a computer won't turn on and often very few clues about what might be the problem. The only symptom is usually the simple fact that "nothing works" which isn't much to go on.
Add to this the fact that whatever is causing your computer not to start could be an expensive part of your PC to replace - like the motherboard or CPU.
Do not fear because all may not be lost! Here's what you need to do:
Is it plugged in?
We make no apologies for starting with the absolute basics, since overlooking this simple check has caught out even the most experienced computer users.
So if your PC seems to be completely dead, check that its power lead is plugged into both it and the mains socket — and that the mains socket is switched on.
If you’re using a multi-plug adapter, check that it’s not to blame by either removing it from your set-up completely or swapping it for another you know is working.
And never forget the most obvious check — is there mains power to your property? Power cuts can happen at any time and the mains circuit breaker can trip without you realising. So if nothing else that runs on mains power is working, that’s almost certainly why.
Is it switched on?
Yes, blindingly obvious, we know, but you’d be surprised… Some desktop PCs also have a power switch on the power supply unit (PSU) at the back of the case, so check that it’s switched on. Check your monitor, too — and, if you know how, check that it’s set to the correct input. If not, that would explain why it’s blank when your PC appears to be working.
The same applies to any external peripherals that run on mains power. Those with physical switches are easy to check, but those with buttons you need to press and hold to power-up can be problematic, so refer to their instructions, if need be.
Has the fuse blown?
All AC mains plugs have a fuse inside and when one blows, no power will flow. So check the fuse in the plug for your PC’s mains lead and that for any other devices. There’s no easy way to check if a fuse has blown, so it’s usually simpler to replace it with one of the same rating — never be tempted to us a fuse greater than the size shown on the plug.
DC mains adapters (the large black plugs used by certain peripherals) don’t have accessible fuses, so if you suspect one that’s the problem, you’ll need a new one adapter.
PC motherboards and PSUs also have fuses, but neither are user replaceable. Instead, you’ll need to seek specialist advice or go back to the manufacturer — or just replace the entire component. That’s relatively simple for a typical desktop PC, but much more involved for a laptop.
Did you upgrade something recently?
If you’ve been working inside your PC to remove or add a component, it’s usually no coincidence when something doesn’t work properly afterwards.
Assuming you know what you’re doing with a screwdriver (else why were you inside your PC in the first place..?), go back and check what you were working on.
Obvious points of failure are failing to connect a power lead to a new disk drive or expansion card, or disconnecting a power lead from the motherboard because it was in the way and then not reconnecting it afterwards.
Does your PC beep when it powers up?
If your PC has power, lights up when you switch it on, but then does nothing but beep and grind to a halt, there’s a fundamental problem somewhere.
Those beeps are called ‘beep codes’ and they’re used to indicate a fault that’s preventing the computer from booting. You’ll need to search online to find out what the codes mean for your particular PC, but common causes are an improperly fitted components, such as a memory chip or expansion card not sitting in its socket, or a newly fitted component that isn’t compatible with your computer.
If the beep code matches something you’ve been messing with recently, then it should be easy to address, else you’ll probably need specialist assistance.
Will Windows load?
It’s far from unknown for Windows to stop working for no apparent reason, even when it was working perfectly the day before. Fortunately, Windows has its own collection of troubleshooting tools to fix such situations.
The simplest is to boot your PC from your Windows installation or system record disc and select the Repair your computer option. We’ve covered this approach (and other similar options) before, though, so take a look at our “Bad computer crash? Fix Windows problems with System Restore” guide for more advice.
Are my files still safe?
One important thing to remember if your PC won’t work is that your files are almost certainly safe. Unless the problem is a hard drive failure (which your PC should warn you about when you switch it on), there’s nothing that can damage your data.
The worst-case scenario if you’ll need to remove your hard drive and fit it to a new PC to get at your stuff and that’s a really simple process.
