Fix my website to be mobile resonsive and mobile friendly again!

I need someone with experience in PHP and make my website responsive and mobile friendly again. It was mobile with all the tools that it have integrated and all are gone right now. And sliders are not anymore mobile responsive. I really don't why happened that but I believe when website suffered some modifications the mobile version just didn't function anymore.

I attached some pictures too explain what is all about. I attached some pictures about how was my website with all the tools that it had on mobile and how it looks now,

The pictures with arrow are showing how it must look the website with all the mobile tools. The picture without an arrow it show how the website look now on mobile not working the mobile tools.