One day you power on your PC , no things displayed on screen! What are the basic steps you do to discover the problem?

1- Test Your Monitor Before you begin more complicated and time consuming troubleshooting with the rest of your computer, make sure your monitor is working properly.

2- Verify that your PC has fully power cycled. In other words, make sure your computer has completely reset - make sure that it's coming on from a completely powered-off state.

Often times a computer will appear to "not be on" when actually it's just having problems resuming from either the Standby/Sleep or Hibernate power saving mode in Windows.

Note: You can power off your computer completely while in a power saving mode by holding the power button down for3 to5 seconds. After the power is completely off, turn on your PC and test to see if it will boot normally.

3- Troubleshoot the couse ot the beep code if you're lucky enough to get one. A beep codewill give you a very good idea of exactly where to look for the cause of your computer turning off.

4- Clear the CMOS Clearing the BIOSmemory on your motheboard will return the BIOS settings to their factory default levels. A BIOS misconfiguration could be why your PC won't startup all the way.

sounds like the system did not pass the self test. it

needs to have CPU, graphics, RAM, and keyboard. make

sure all these are plugged in and have power plugged into

it. CPU gets it's own plug, fan gets a little one. Graphic

cards can need0-2 plugs. everything else just needs to

be seated properly.

check montior  check all power cables 

CHECK the power supply   

check the Ram  and clean it 

check VGA card  and remove it  and reinstall 

check the battery Bios 

A nice question asked by most of the employers

1.Check the Power main power for the Computer and display as well

   I. If main power is ok but power supply fan is not spinning the go ahead and check the power supply first, You can use PU tester to test the power supply. If you don't have PU tester then simply short pin14 &15 (green and black) to check if fan start spinnin or not

   II. If power supply is ok then go ahead and check the motherboard. The best way to test motherboard is by using MOBO tester, if MOBO tester is not availabe then you can start manually checking the mother board, if there is no display then most likely the problem is with the CPU or sometimes RAM in older motherboards when you don't get any beep code.

2. You can also consider checking basic things too like if the VGA cable is properly pluged in or not. If there is a separate PCI card installed in the computer then you don't get display from internal VGA port unless you disable that from the BIOS.

The first thing i would like to check for display is "RAM" change the RAM , if it doesnt payoff, change the slot of RAM, might be slot is malfunctioning, another thing is may be some USB device (Data Traveler. keyboard,mouse) is conflicting, or anyother peripheral device might conflict, try to de-assemble all peripheral device, and start connecting each one  by one, and turn on the PC on every connecting peripheral, if it doesnt work either, then try to change power supply, some time power supply causes display problem, at the check motherboard (built in VGA), try getting display on another PCI or PCI express VGA Card... if this doesnt work either... then i am afraid get your motherboard  repaired or replaced....

1. If it's a desktop check the vga or hdmi cable if it's firmly connected or try changing it if same problem try the monitor, if it's a laptop connect the loptop to an external monitor

2. Clean the RAM

3. Check the Video card if its a desktop

4. If it's a laptop the VGA chipset is overheated the chipset may be misaligned and need's a technician to replace or realign

1. Check if the screen it is working correctly, the problem might be the VGA Cable or HDMI 
2. Make sure that all the power sources (power supply or battery) is working correctly the problem can be just the power cable.
3. if the computer made a beep sound you can search in google about this sound (or remember what was the last hardware change you have made then undo the change)the problem might be the RAM Memory, Graphics card, CPU Fan or the CPU it self.
4. Disconnect all the devices which is connected by usb.
5. try to enter the BIOS by click on the F2 or Delete key and rest the configuration to the default (or rest it by removing the CMOS Battery or in whatever the way in your computer)
6. Check the capacitor in the motherboard

You can turn off your computer by long press on the power button

1- check cable power 

2- check power for screen and CRT Cable

3 - check power supply if it work 

4 - motherboard from power supply connector side 

5 - CPU fan 

6 - Ram bank and clean it