hi I can't restart my iphone6plus

Hi aref4566,

Welcome to Apple Support Communities.

First, try to follow the steps in Restart your iPhone.

If you can't, follow the steps in Force restart iPhone - Apple Support.

-Jack

Probably a battery issue and/or a Power button issue. You should take it to an apple store or authorized retailer. However, the iPhone 6 Plus is outdated and apple may just send you a new phone.