itunes cant re-add music from itunes to iphone after it was deleted directly from iphone

Using iphone 8 iOS 12.4.1 and latest itunes on windows10.

I've been getting issues with the music app on my phone after transferring files using itunes. I have a mixture of purchased music through itunes, and also music ripped from CD's. Around 15 albums now have reverted to showing numbers rather than letters, and I now have around 30 albums all showing artwork from Fleetwood Mac's Rumours album. I followed advice from a few threads and deleted the tracks from my iphone, but now I am unable to re-add them to the iphone from itunes. Some of these are purchased from itunes, and when i have tried to re-download them they appear greyed out in the itunes store and I dont even have the option of paying for them again, even though i shoudnt have to!

been looking through the threads but cant find anything that helps, so if anyone has any ideas, i would appreciate it.