exclamation marks appearing on itunes windows 10 next to music stored on device

The other day I decided to put all my music on my iphone, but then I realized that I put in too much music. I went to settings and deleted all music from my apple music app but now when I see all the music on itunes, they all have exclamation marks near them and I cannot delete them. When I try to put the same file back on the iphone, it doesn't transfer. The itunes music stored on my pc still plays, but the music on the iphone does not.