We'll need a little more info. Assuming that you're a prepaid customer, did you top up using a top up voucher or did you top up online by logging into your prepaid self serve account? Are you reactivating a suspended prepaid account?
You can check the activity of your account by logging in to prepaid self serve. Sometimes the system takes a bit of time to process payment. Let us know if service has resumed, or if you're still without service.