If everything was working ok before and this problem just cropped up out of the blue then you'll probably need to contact 48 support for assistance.
See the links in my signature below.
What happens if you do a manual search for networks?
Can you see and connect to 48?
Does reseating the SIM help at all?
Did anything change on the phone - e.g. software update, settings changes, factory reset etc.?
Are your APN settings correct?
When you can text again text "APN" to 50048 and follow the instructions to ensure that they are:
