frozen touch screen

There could be a lot of reasons for that to happen.  If your device is older and has had a lot of updates without a factory reset.  That can lead to unusual bugs.  So much cached app data over time can do the same.  To rule out hardware, a factory reset without restoring a backup is always recmended.  If it is hardware related, it will continue after a factory reset.  Then you either want to request warranty service on the device from the manufacturer, use your phone insurance plan on it if you have one, or consider a third party repair place like your local cellphone repair shop.  It ultimately be better off replacing it though.