Missing album artwork after deleting iTunes cache folders

After trying to solve an issue i had where new artwork i inserted didn’t show up, i read on this same forum that it was safe to erase the cache folders. Thing is i did it and now ALL MY ARTWORK on my albums disappeared, and only the songs with it embedded in the mp3 file they come from remains. If it initially shows up it disappears after i restart my imac. HELP PLEASE

[Re-Titled by Moderator]

Original Title: after having deleted some itunes folders my album artwork i manually inserted is no longer displaying and keeps erasing itself