Hey @Kerryann23! Is it not letting you call people either or is it just receiving calls that's causing issues? Turn off your device. Take your SIM out, give the gold contacts a rub and put it back into this phone.
Is your phone crashing whilst using an app or just when on your phone in general?
As a process of elimination can you put your phone in Safe Mode.
This will help to determine if an app is causing this.