Let's check to see what account purchased this song:
1. Open iTunes
2. Highlight one of the items you have purchased (You can find your purchases in your Purchases playlist).
3. Choose File > Get Info.
4. Click the Summary tab.
The Account Name area will list the account used to purchase the item. Unless you have changed accounts, this is your iTunes Store account name.
Now that we know what account purchased this item, try logging into the iTunes Store with that account. If successful, proceed to your purchased page to download the song again (you'll have to delete the original before downloading again, but make sure it is in the purchase history first).
Thanks for trying Matt, but I had already tried all of that before I posted. It doesn't even show up in the purchased page, although when you get the information for the song it gives me the exact date it was purchased 11/6/06 I believe. I have read somewhere it had to do with protected files, or the way downloaded files were protected back before 2009, but I am not positive about that. I haven't checked other old downloads, but I'll bet that its the same thing, as NONE of the older downloads appear on my purchased page. Only things downloaded in the past couple of years appear there.
Thanks anyway though.
Thanks for the follow up, and again for the detailed information. Due to the nature of your question, I think it would be best if we can get you in contact with someone who can look into this. You may find more information by using another one of Apple's support resources - http://getsupport.apple.com