The following article may be helpful in getting Home Sharing back on track with its setup.
You might try skipping to step 6, as it may be the most relevant step for your particular situation.
6. Quit and reopen apps and iTunes
If connectivity issues persist, quit and reopen iTunes on your computer. Then, quit and reopen the apps on your iOS device. (http://support.apple.com/kb/HT4211)
If this does not get things up and running, I'd recommend following all steps outlined in the article.
All the best,