When was it working ok last?
What changed in the meantime?
What make and model of phone is it?
What exactly is/isn't working?
Connection to the 48 network - i.e. signal bars?
Incoming/outgoing calls?
Incoming/outgoing texts?
Mobile data?
Have you tried reseating the SIM in case that helps,
Can you try your SIM in another unlocked phone to see if it works there?
If you need to contact 48 support about this then see the links in my signature below.
