You'll need to post a bit more info than that if you want assistance from the Community Forum.
For example..
Are you just joining 48?
If so then maybe check the Starting With 48 FAQs:
If you're not new then when did your SIM/phone work ok on 48 last?
Did anything change since then - e.g. new phone, settings changes, factory reset, software update, returned back to Ireland after roaming abroad, etc.?
If you do a manual search for networks can you see and connect to 48?
If you need to contact 48 support about this then see the links in my signature below.
