Music library deleted

I turned on my ipod touch 5th generation a little while ago and all of my music wasn't in my library, except for a few albums I had downloaded with Apple Music. I plugged it into my computer and all of my purchased music synced back onto it, but for some reason my albums I had downloaded on my computer from cds won't sync with my Ipod, even though they are in my library and I used to have them on it. Does anyone know how to fix this?