Apple downloaded music

First check they are not hidden 

Hide and unhide Music ...

https://support.apple.com/en-ca/HT208167

Or ....

Go to Settings > [your name] > iTunes & App Store.

Tap  your Apple ID at the top and sign out 

Close Settings.

Go back to Settings and sign back in 

Go to the iTunes Store to find the music, tap the cloud icon to download 

it says I have to buy it all again.

Is that what it actually said, "You have to buy it again"? :-)

Anyway, if the songs are still available in the iTunes Store, you can download fresh copies at no cost. Follow these steps:

http://support.apple.com/kb/ht2519