Please do try these troubleshooting steps that may help.
- Start by doing a hard reboot, remove the battery and unplug the AC adapter then press and hold the power button for 20 seconds then try booting it up again.
- If this will not work, do test the AC adapter if it's working properly. Remove the battery and power the laptop with just the AC adapter connected and see if it will boot up or not. do also try a different AC adapter that has the same voltage and see if it will work or not.
- Proceed with reseating the RAM's if trying a different AC adapter will not work, remove them all for couple of seconds then put them back in making sure everything is seated properly.
- If it will still not work, connect an external monitor and see if you'll get any display from it. If there's a display on the external monitor that could mean that the problem is the built in display.
- If it will display on the external monitor, press the Windows key + P at the same time and select Computer Only and see if it display back on your built in display.
- But if there's still no display on the external monitor that means the problem lies in the motherboard.
Actually I did everything you said but unfortunately nothing changed but when I press the button on first the fan works and after 2 sec turning off and about 5 to 10 sec again fan working also still have a black screen. So when I take RAM of laptop makes beep beep this beep it's mean the motherboard is ok I wish someone can help me thanks.