my home sharing used to work, but now when I turn it on on my iphone, the little circle showing the loading always gets half full and then jams. What is going wrong? Thanks

Hi, my home sharing network used to work fine, but no longer. I want to listen to podcasts on my iphone that I have downloaded onto itunes. When I turn on home sharing the little circle indicating loading only gets half way around and then jams. I have an iphone 4s and a microsoft computer running windows 7.

Any help would be greatly appreciated, thankyou