I'm having the same problem, even after I got this email from iTunes Support (and no, I still can't unhide my songs! iTunes is really sucking lately and ******* me off!!!!!!):
Welcome to iTunes Store Customer Support. My name is Sandhya.
To confirm
my understanding, that you are unable to play the song and the song is not
listed on your purchased songs. I know it is important for you to get this issue
addressed at the earliest. Not to worry, I will be glad to assist you with this
concern.
Mark, I would like to inform that the song is hidden and I
would request you unhide the song, and try to play the song.
To unhide
an item on your Purchased page, follow the steps in this
article:
http://support.apple.com/kb/HT201322
I am sure the above
information addresses your concern. If you have any more questions or concerns
regarding the account or the same issue please reply to this email, I will be
happy to help you.
Thank you for contacting iTunes Store Customer
Support. Have a nice day!
Sincerely,
Sandhya
iTunes Store
Customer Support
http://www.apple.com/support/itunes/ww/
Please note -
I work on Sunday - Thursday, 08:00 PM to 05:00 AM CST.