why my LG G2 suddenly shut down and didn't turn on again

[AC Question]

suddenly my LG G2 shut down and after that i tried to make it on but nothing happened. i need to turn it one again. i am very gently with my phone since 1.5 year ago

 

[belodion]

Try pressing and holding Power for a minute or so.

If no good, try pressing and holding Power and Volume Down for half a minute or so. Then try rebooting the phone.
If you prefer, remove and replace the battery, though not very easy to do on the G2. Then try rebooting.

If no good, the battery or some internal part may have failed.