You'll need to post a bit more information.
Did it ever work?
If so when did it stop working?
What changed on your phone?
Software update?
Settings changes?
If it never worked or you just joined 48 then did you configure your data settings correctly?
https://community.48months.ie/t5/The-Knowledgebase/My-Internet-is-not-working/ta-p/45928Hope this helps.