iPhone 4S home screen not working. Have to wait battery drain.

Hello,

First of all, the lock/unlock button (upper one) of my iPhone 4S doesn't work.

Sometimes I am in an app (safari, whatsapp, etc) and I try to go to the home screen and the phone just get stucked in the app. I can't access to multitasking and can't turn it off using assistive touch (doesnt show the screen of it). Can't access to other apps (using the control center tried to open camera or calculator)

So with assistive touch I locked it and when pressing home button does nothing. It is just black. I do receive calls and sound alerts, it vibrates when using the silent switch but screen remains black.

I have to wait the phone drains the battery because I can't use bottons to reset.

This is the 3rd time I have this problem. Started to happen when updating to the latest iOS.

What should I do? How can I reset it without using buttons?

Thank you.

Edit > PD: Sorry for my english.