You'll need to post a bit more info about the issue than that.
Was it working before?
If so when did it stop?
Did anything change on the phone such as a software update or settings changes?
If you do a manual search for networks what do you get?
Have you tried switching off, taking the SIM out, gently cleaning it, reinserting it, switching on and then trying a manual search for networks to see if you can see and connect to 48?
Do you have an active membership?
If necessary contact 48 support - see the link in my signature below.
Hope this helps.