Hello t.please47,
Thank you for using Apple Support Communities. It's my understanding your iPhone has been disabled, it's shutting down unexpectedly, and it's not connecting to your PC. I can surely see how this would be concerning. I want to help get your iPhone working again.
Please try the steps in the "Erase your device with recovery mode" section of the following article:
If you forgot the passcode for iPhone, iPad, or iPod touch, or your device is disabled
Have a wonderful day!