Troubleshooting PC hardware problems generally follows one of two step-by-step paths. If the computer will not boot up, then stepping through the boot-up process can narrow down where the issue lies. If the computer boots up, but a particular piece of hardware (a sound card for example) is not functioning, then a narrower set of troubleshooting steps can be used to determine the problem with that single piece of hardware.
1). Turn the computer on. If the power light comes on and/or you hear fans and discs spinning up, then the power system is good. If not, then the problem lies in the power cord, power switch or power supply unit.
2). Watch for the BIOS splash screen to appear, if the power is good. This is a screen with a manufacturer's logo, which will tell you somewhere on it that you can press F2 to enter setup. If you only get a blank screen or a blinking cursor and the splash screen never appears, then your motherboard is likely the problem and it will need to be replaced.
3). If the BIOS screen does appear, try pressing F12 to boot into Windows Safe Mode. If nothing happens, you get a black screen or you get a hard drive error message, then the problem is likely your hard drive and it will need to be replaced.