The screen is definitely replaceable. The only thing though is that the screens are very expensive, costing upwards of $300 sometimes, depending on the quality. The “iPhone is Disabled” message usually happens when the phone’s internal clock resets due to an extremely discharged battery, though it could be a different cause, and can be fixed by connecting to iTunes and restoring it by going into restore or DFU mode. As for the phone not ringing out or charging, that seems like a problem with the speakers and lightning port. Overall, this phone seems to be very abused, and likely will be very costly to repair. You could take it to Apple and see if you can get it repaired or replaced, or you can go Third-Party, and although it will likely be cheaper, the parts might not be the best quality. Since the phone is new, I would recommend going to Apple instead. Next time, though, get a case and screen protector. Rhinoshield makes great quality screen protectors and cases.