Recovering deleted unauthorized music I purchased

I synced my iPod touch to my computer and I haven't synced it in a few months. When I plugged it into my computed, the dialog box popped up stating "this computer is unauthorized, would you like to authorize it?" because it was an account that hasn't been used in about 10 years. So i did authorize it, and it synced 67 out of the 68 songs I had onto my computer. Afterwards, another window popped up saying that the one song that didn't get synced was still unauthorized, and at this point there was nothing I could do, so the song got deleted. I am certain that I am the one who purchased this song, along with the rest of the songs. Is there anything I can do to retrieve it? Because I don't think it's right that I will have to pay for the song again if I want it back.