iTunes won't let me sync my music library :( Help please!

At first I transferded my entire library with no problem, but there were songs duplicated so I started deleting them on the phone one by one. I got tire of the process and searched online for a "delete entire music library" option and found it in the settings. I try now to tranfer my song but it won't let me, only the ones I bought. I've (also by mistake) insted of pressing the 'delete' button I pressed the 'delete purchase' and now the song won't even appear on my 'purchased songs' list 😟😢