I cannot use mobile data

I m travelling around Europe, before leaving Portugal I recharged my card and I had everything working perfectly. Then I reached Slovenia and I could use mobile data for one day then I couldn't use it . But I can still make calls and send SMS. But with the mobile data I still have 500mb of data left. I am a moche legend user, so I still have some data left . But I cannot access it. Can anyone help me with this