Downloaded podcasts and music not playing offline

Hi there,

I have always been listening to my downloaded podcasts on my commute and never had any trouble. Yesterday, I listened to the first half of a podcast that I'd downloaded (to be played offline). It worked fine, however this morning, trying to play the very same podcast offline says that I need to be connected to Wi-fi. It has never done this before and so weird to happen overnight when I haven't done any updates or changed any settings.

I tried all my other podcasts which I had already downloaded and they all did the same thing. Then I tried to play my music on iTunes, music which I had paid for and downloaded (and played previously)... and that didn't work either.

I have tried to turn my phone off and on, and I have the latest software update so I am a bit stuck now. Please help as I am going to go mad on the tube!!

Thanks in advance!