Is your phone unlocked for use on any network?
Is data roaming enabled?
Have you tried powering it off and on again?
When you manually scan for networks scan you see 48 (or, if not, O2) and connect to it?
Do you get any signal/signal bars?
What do you mean by "change the SIM"?
Did you get a replacement SIM or have you just moved to 48 from another provider?
If necessary contact 48 support for advice
http://www.48months.ie/help#ask-a-48-agent
You probably shouldn't post your personal details (ICCID and phone number) on a public forum.
Hope this helps.
