My phone is not working is suddenly switch off

@thalladeepa could be a lot of things. Start off by checking the basics.

First check that your phone charger supplies the proper voltage. After that, you need to check your charging cable. Check to make sure 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. If none of this works, get a USB ammeter and see if your phone draws any amperage from the charger. If it does not, it is possible that this is a charging port issue or a bad battery.

If that does not do anything and everything checks out ok, time to disassemble your phone. It could be the charging board, but it can also be the flex from the charging board. Those love to come loose and even tear. Check it closely.

Once you've checked all that and still no resolution, you will need to get a step further. This time you need to check the power components on the board.

The location of the components is within the Blue rectangle.

If you find anything you need further help with, post some pictures of whatever issue that is, with your question. That way we can see what you see. iFixitでの質問に画像を追加する方法

Ultimately, what I would do, is to take a chance based on my own experiences. I'd replace the battery, the charging board and the flex for sure.

While you work on your phone, 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.

Repair is War on Entropy!