Hi zahirul99,
Thanks for contacting Apple Support Communities!
We understand that you're unable to disconnect your calls and turn off your iPhone, correct?
It sounds like you may be using the side button to disconnect your calls, is that right? If so, check out this resource which will show you how to troubleshoot your iPhone buttons: If a button or switch isn't working on your iPhone or iPad - Apple Support
If you're unable to disconnect your calls via the iPhone display, this may help you as well: If the screen isn't working on your iPhone or iPad - Apple Support
"If your screen is too sensitive or responds intermittently to touch
- Restart your iPhone or iPad.
- Make sure that your screen is clean and free of any debris or water.
- Disconnect any Lightning or USB-C accessories. If your screen works after removing an accessory, try using a different outlet, cable, or charger.
- Remove any cases or screen protectors.
Contact Apple Support
If your screen still isn't working, you might need to set up service for your device. Contact Apple Support."
Take care!