You'll need to post a bit more info than that if you want help.
For example...
What make and model of phone is it?
Was it working before?
If so when did it stop working?
Did anything change? E.g. phone software update, settings changes, roaming abroad?
What are the symptoms?
No signal bars?
What happens if you do a manual search for networks?
Can you see and connect to 48?
Or are you just joining 48 and trying to get started?
Is the phone unlocked for use on all networks?
