Home sharing to iPad has stopped working

Last night, my apple tv demanded I submit my password. So I did, twice (definitely correctly), but apple tv said it was incorrect, and that I should visit apple.com to sort out the problem. Can't find a solution, but I have checked all my devices and my itunes account, and they are all still using the correct password. Annoyingly, however, my iPad now won't play movies from my itunes on my laptop, because I 'do not have permission'. I can only assume these two instances are connected, as I regularly watch itunes media on my iPad. Any help would be hugely appreciated, thank you.