When your computer won't start

A computer that won't start is frustrating. Fortunately, many startup problems are easy to diagnose and fix.

Step 1: Check the power supply

For desktop computers

  • Check the plug and the outlet
  • Check the power cable at both ends
  • Check the power switch on the power supply (I = on, O = off)
  • Check the LED indicators on the motherboard

For laptops

  • Is the adapter connected properly?
  • Try running on AC power without the battery
  • Charge the battery for at least 30 minutes

Step 2: Interpret POST beeps

Beeps during startup indicate what is wrong:

AMI BIOS:

  • 1 short beep: DRAM refresh error
  • 3 short beeps: base memory error
  • 1 long, 2 short: video card problem

Step 3: Fix a black screen

Check the monitor

  • Is the monitor turned on?
  • Is the correct input source selected?
  • Try a different cable or port

Reset the RAM

  1. Shut down and unplug the computer
  2. Remove all RAM modules
  3. Put one module back and try to start up

Step 4: Windows recovery options

Start in Safe Mode

Force the computer to shut down three times in a row during startup. Windows then automatically starts in the recovery environment.

Use System Restore

Go to 'Troubleshoot' > 'Advanced options' > 'System Restore'.

Command Prompt commands

  • sfc /scannow - Repairs system files
  • bootrec /fixmbr - Repairs the Master Boot Record
  • bootrec /rebuildbcd - Rebuilds the Boot Configuration Data

Step 5: Hardware diagnosis

  • Replace the CMOS battery: Can cause startup problems after 3 to 5 years
  • Minimal configuration test: Keep only the motherboard, CPU, one RAM module and the power supply
  • Test the hard drive: Listen for unusual noises

Frequently asked questions

My computer makes no sound at all. What can I do?

This usually points to a power problem. Check the plug and the outlet. If that doesn't help, the power supply is probably defective.

The computer beeps several times. Is this serious?

Beeps are actually good news: they tell you what is wrong. They usually point to a RAM problem. Try removing the RAM modules and reinserting them.

Windows no longer loads, but I don't want to lose my files.

Your files are probably still intact. Start up in Safe Mode or use the Windows recovery environment. You can also connect the hard drive to another computer to back up your files.