iPad mini/iTunes problem

I'm having real difficulty finding an answer to this problem and since the device is out of warranty, Apply want to charge £25 for me to even report the problem.

We have ONE film that we've purchased on this device but it was accidentally deleted. Everyone tells me I can simply download it from the store again for free - however, the "cloud" icon is greyed-out. We decided to bite-the-bullet and buy it again, but that won't work either, it says we already own it.

I've been told that I need to fix this by connecting to a PC - but this iPad has always been stand-alone and I don't have iTunes (or anything else) loaded on a PC.