Why can't I update apps or use data?

I have a Blu Studio Energy 2 dual sim that I use when I travel. I used it for 2 months in Feb and March in Italy and at home in US before I left. This time the apps were telling me to update before I left (whatsapp, snap chat, facebook, skype). None were able to do it (AT&T at home WIND in Italy). I also could not use cellular data. Here in Italy- still can't update or add apps or use data on WIND. I don't know what to do (I usually use Iphone so this is not familiar to me). Can't find anything online. Thanks.