All of my purchased music is gone.

Just yesterday, I refurbished my windows 8 hp computer because it had problems freezing and etc... Anyway after it was refurbished, I downloaded the itunes store from apple.com and it was working fine. I hid all of the music because I didn't want them to be all over my screen. Just today I went into purchased and all of my music I bought from the apple store was gone. I really REALLY hope it's possible to recieve all of my music back again. Thank You so much, Dylan