I tried all the fixes suggested for data roaming and still did not work - fed up I am paying 48 for the service and they just fibbed me off for help from the community ( I am not paying the community for the service !) fed up and phoneless in France
Are you on a Guido membership? Are calls and texts working ok? If yes to both then check your internet settings and if the apn field has changed from 48months.liffeytelecom.com then edit it, change it back to that, reboot and see if data starts working. If it doesn't then you'll have to contact 48 support and ask them about it. Unfortunately this is a common enough problem for some users. I.e. data doesn't work when it should when roaming in the EU on a Guido membership.
Hope this helps.
I am not a 48 employee so if you need to contact 48 support then use option 3 or the chat facility here.