Why my laptop not turning on?

@meenakshi16 you forgot to tell us if there are any LEDs that light up or if your laptop give you any sign of live. TRy this first. Disconnect the power from the computer by unplugging the power cord from your computer. Disconnect all external devices from the computer. Remove the battery (if you can ) Now hold the power button depressed for about 30sec-1min. Reapply the AC power adapter and see if your computer now shows any sign of life.

Next you want to check your power supply. Make sure it has the proper voltages. Check to make sure that the pins are not bend etc. After that, check the charging port. Clean it of any debris etc, use a few puffs of air to clean it out. Make sure there is no corrosion, debris etc. that prevents it from working. If none of this works, get an ammeter and see if your laptop draws any amperage from the charger.

After that, you need to check and see if your motherboard even gets power. For that of course, you need to open it up. Since iFixit does not yet have a guide for it, use something like this video to work on it. Post Some good pictures of what you see. That way we can see what you see 在已经存在的问题里加入图片

While you work on your laptop, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Can be a Keyboard issue. The power button is on a keyboard, and if he fail, the laptop don't boot up.
Try this My keyboard is not working