Do you stlil have balance on your account? You can check in the self-serve, if need be you may need to make a payment via credit card or visa debit or prepaid voucher.
Have you tried turning the phone off, removing the battery breifly, then re-inserting the battery and turning the phone back on?
There had been an issue before regarding incoming calls, shown on this thread. I had previously been unable to receive incoming calls and fixed it by turning off the LTE in my device.
Verify your self serve if your plan is still active, Pull out battery/sim for few seconds, Power cycle phone, search network manually, check your phone settings, do not disturb, automatic rejct, try again
