No signal or 4G after replacing my phone battery.

Hello, I recently replaced my phone battery. Now that I've turned it back on it said my SIM is not registered with my network and I can only make emergency calls. Another fixer from a previous question suggested I replace the SIM card tray but still no dice. Do I need a new SIM? In the process of fixing my phone have I done it other damage I will need to go and fix? Any help is much appreciated. Cheers