ARCHIVED: Why won't my Windows computer start?
On this page:
- Electrical problems
- BIOS (CMOS) problems
- Problems with booting
First, make sure the computer is getting power. If you don't see lights and hear sound when you try to turn on your computer, first check the power cables. If your system has a 110V/220V switch on the back, make sure it's set firmly in the 110V position. Also, if you use a surge protector, make sure it's turned on and you are receiving power from your wall outlet.
If all of these connections are fine but your computer still does not respond, its power supply may be damaged. In this case, take your system to a repair shop to have it diagnosed and repaired.
Note: Sometimes the cooling fan will spin even though the power supply is broken.
If the computer lights up and beeps, but the monitor remains dark, make sure the monitor is turned on and getting power, and that the monitor, keyboard, and other peripherals are firmly attached to the CPU.
BIOS (CMOS) problems
If you do see the power lights come on and hear the hard disk start to spin, check for a BIOS (Basic Input-Output System) error message on the screen. Your computer's BIOS has a built-in program called the POST (Power-On Self Test) that checks all your hardware when you turn on the computer. The BIOS then stores information about the hardware in an area of memory that is not erased when you turn your computer off; this non-volatile memory is referred to as the CMOS RAM.
When the BIOS finds something wrong with your computer, it flashes an error message on the screen or makes your computer emit a series of beeps. These beeps are diagnostic messages. Different brands of CMOS have different beep patterns; see If my computer beeps and fails to boot, what do the beeps mean? Moreover, depending on the brand of BIOS your computer has, diagnostic messages that appear on the screen may be either informative or merely cryptic.
If the BIOS cannot access the hard drive in your system, it will usually alert you to this fact. However, this access failure does not necessarily mean that your hard drive has failed, or that you've lost all your data. More likely, a battery failure in the CMOS RAM has caused the BIOS to lose your hard drive configuration settings. When this happens, you'll need to get a new battery and restore the CMOS Settings.
The settings in the CMOS RAM for your hard drive (such as the number of heads, cylinders, and sectors per track) depend on the brand and model of the drive. Many hard drive models allow several different configuration settings; however, if you use different settings from those used when the drive was set up initially, the drive will be inaccessible.
In most cases, a BIOS error means you will either have to investigate your CMOS settings or swap components. Usually, you will need to take the computer to a technician. If the boot failure occurs after you have just installed or moved a video card, power down and push the card firmly into its slot, and then try restarting.
Problems with booting
If your computer gets past the POST stage, the problem is most likely something in the Windows boot process. At this point, it's useful to use one of the options below.
Using Recovery Mode in Windows 8
In Windows 8, if your computer does not start, a Recovery Mode should
come up with options to troubleshoot your computer. If it does not,
restart the computer; as it begins to load, hold down the
Shift key and press
Booting into Safe Mode for Windows 7, Vista, or XP
If you can boot into Safe Mode, you can set it to not load certain drivers, disable startup items, run ScanDisk, and use a number of other diagnostic tools.
For help, see Microsoft Support.
Using System Recovery Options in Windows 7 and Vista
Using the Recovery Console in Windows XP
If you have Windows XP, you can use the Windows XP installation CD to reach the Recovery Console and access DOS (the command prompt).
Your computer may also be infected with a virus, in which case UITS recommends reinstalling your operating system. For more, see Why do I have to format and reinstall Windows after my computer is infected with a virus?
Last modified on January 03, 2013.